MailerSend

OPERATIONAL

Since Feb 2026 · 25 incidents · status.mailersend.com · checked just now

User reports

Visitors who said it's down for them, per hour over 24 hours. Not from the status page. Never counted in grades.

…

Compare Add to stack Status page

GradeA+Last 90 days

A+PRODA+SHIP

Overview

30d 90d 1y

Admitted uptime

Customer time not hit, by the provider's own account. Regional and partial incidents count in part.

100.000%Grade A+

Incidents

Everything posted on the status page except scheduled maintenance.

00 Sev 1

Fully down

Most customers down, by the provider's own account.

Median fix

Median time to resolve. Half of incidents were fixed faster.

–

Longest

Longest Sev 1–2 incident, start to resolved.

–

Since last

Time since the last counted incident was resolved.

1795d 3h

By area

A+Production

0INCIDENTS

0mAFFECTED

Your users are hit: apps, APIs, databases, inference

Worst, 90dNothing.

0 in the last 6 months.

A+Shipping

0INCIDENTS

0mAFFECTED

You can't deploy, build or manage: CI, CLI, dashboard, auth, billing

Worst, 90dNothing.

0 in the last 6 months.

CleanSev 3–4Sev 1–2No data

Trend, last 12 months

0 in the last 6 months.

–

Severity mix

Sev 1 · Lights outProd site, API or database down, or data loss0

Sev 2 · BleedingProd degraded or partly down0

Sev 3 · Can't shipCan't deploy, build or manage it0

Sev 4 · PapercutDocs, status page, slow dashboard0

When it breaks

Start times, last 12 months, UTC.

Mon

Tue

Wed

Thu

Fri

Sat

Sun

0006121823

What breaks

No components named in the last 12 months.

Communication

Updates each

Status page updates per incident, on average.

2.2Last 12 months

Update gap

Median time between status page updates during an incident.

54mLast 12 months

Postmortems

Sev 1–2 incidents with a published write-up.

0 of 17Sev 1–2

Incident history

Show all 25

Feb 19, 20260mSEV 4

Technical issuesAn unspecified technical issue in the MailerSend app may have caused problems for some users; the text gives no API or sending impact.AI-graded

Why this grade

RULES · SEV 1
Sev 1 from the incident title (no components listed)
CLAUDE · SEV 4 · UNCLEAR · LOW CONFIDENCE
An unspecified technical issue in the MailerSend app may have caused problems for some users; the text gives no API or sending impact.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

3 updates

09:45 UTC · investigating
We are currently investigating this issue.
12:05 UTC · resolved
We experienced a technical issue in the MailerSend app that may have caused problems for some users. The issue has been fixed. We apologize for any inconvenience.
12:05 UTC · resolved
We experienced a technical issue in the MailerSend app that may have caused problems for some users. The issue has been fixed. We apologize for any inconvenience.

Source

Feb 19, 20260mSEV 2

We are experiencing a technical issueMailerSend had an outage on 2022-06-02 that stopped email sending through the API and SMTP and blocked access to the whole app. It was caused by a third-party storage provider. A temporary fix was applied at 10:37 UTC, and the incident was marked resolved at 11:00 UTC, with the app back to normal.AI-graded

Why this grade

RULES · SEV 1
Sev 1 from the incident title (no components listed)
CLAUDE · SEV 2 · UNCLEAR · MEDIUM CONFIDENCE
Email sending via API and SMTP was down, and app access was lost, for about 30 minutes after a third-party storage failure; the extent across customers is not stated.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

4 updates

10:28 UTC · investigating
We are experiencing a technical issue causing email sending outage with API and SMTP as well as access to the whole app. All of our engineers are working hard to fix the issue as soon as possible. We apologize for this downtime. We know that you have emails to deliver, so we're 100% focused on resolving this and preventing future issues. You can check the status page for regular updates. Thank you for your understanding, The MailerSend team
10:31 UTC · identified
The issue has been identified and has been caused by a third-party storage service provider. We are actively working on implementing a solution and will let you know when the fix has been released.
10:37 UTC · monitoring
The issue has been temporarily fixed and is now being monitored, we are waiting for updates from our third-party service. If you are still experiencing issues, please contact customer support via live chat or [email protected].
11:00 UTC · resolved
The technical issue has been resolved. The App is back to normal. Thank you so much for your patience.

Source

Feb 19, 20260mSEV 2

The issue has been resolvedA storage problem caused 500 errors on the MailerSend API and SMTP from about 2:46 UTC on 10 August 2022. Some emails could not be sent. SRE found the storage was full, cleaned it up from 4:57 UTC, and added better utilization management and alerts. The text does not say when service was fully normal.AI-graded

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 2 · UNCLEAR · MEDIUM CONFIDENCE
API and SMTP sending returned 500 errors, so some emails could not be sent; the breadth of impact is not stated.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

2 updates

02:30 UTC · resolved
Users were facing 500 server errors on the API and SMTP connections and as a result, were unable to send some emails. The issue has been resolved. Thank you so much for your patience. We sincerely apologize for the inconvenience. A full explanation of what happened is on the way.
07:52 UTC · resolved
Users have faced a lot of 500 server errors from 2:46 am UTC on the morning of 10th Oct, 22. SRE has been paged at 4:31 am UTC and noticed it was a storage issue. The storage caused errors while creating new files in storage for cache or message content, etc. Our SRE team started cleaning up the storage at 4:57 am UTC and put mitigation measures in place so storage utilization would be better managed and would send alerts in case of failure.

Source

Feb 19, 20260mSEV 3

We are experiencing a technical issueMailerSend dashboard was unavailable for about 11 minutes; emails kept processing and no emails were lost.AI-graded

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 3 · GLOBAL · MEDIUM CONFIDENCE
MailerSend dashboard was unavailable for about 11 minutes; emails kept processing and no emails were lost.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

2 updates

12:19 UTC · investigating
We are experiencing a technical issue in the MailerSend app: the dashboard is unavailable. Our team is working to fix the issue as soon as possible. We will update the status page as it's resolved. None of the other pages are affected and emails are still being processed.
12:30 UTC · resolved
The incident was resolved, no emails have been lost during the process.

Source

Feb 19, 20260mSEV 4

We're experiencing a technical issueVague delays in the app were reported for about an hour; the text names no API or email delivery impact.AI-graded

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 4 · UNCLEAR · LOW CONFIDENCE
Vague delays in the app were reported for about an hour; the text names no API or email delivery impact.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

2 updates

20:31 UTC · investigating
We are experiencing a technical issue that might cause some delays while using the app. All of our engineers are working hard to fix the issue as soon as possible. We understand that you have emails to deliver and an apology will not mean much right now. But we wanted you to know that we are 100% focused on fixing the issue and ensuring this doesn’t happen in the future. Thank you for your understanding, The MailerSend team
21:30 UTC · resolved
This incident has been resolved.

Source

Feb 19, 20260mSEV 4

We're experiencing a technical issueDelays while using the app were reported for about an hour with no components named; scope and email delivery impact unstated.AI-graded

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 4 · UNCLEAR · LOW CONFIDENCE
Delays while using the app were reported for about an hour with no components named; scope and email delivery impact unstated.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

2 updates

23:44 UTC · investigating
We are experiencing a technical issue that might cause some delays while using the app. All of our engineers are working hard to fix the issue as soon as possible. We understand that you have emails to deliver and an apology will not mean much right now. But we wanted you to know that we are 100% focused on fixing the issue and ensuring this doesn’t happen in the future. Thank you for your understanding, The MailerSend team
00:26 UTC · resolved
This incident has been resolved.

Source

Feb 19, 20260mSEV 4

We're experiencing a technical issueApp delays of unspecified scope; text says some delays while using the app, with no mention of email delivery or API failures.AI-graded

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 4 · UNCLEAR · LOW CONFIDENCE
App delays of unspecified scope; text says some delays while using the app, with no mention of email delivery or API failures.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

2 updates

05:34 UTC · investigating
We are experiencing a technical issue that might cause some delays while using the app. All of our engineers are working hard to fix the issue as soon as possible. We understand that you have emails to deliver and an apology will not mean much right now. But we wanted you to know that we are 100% focused on fixing the issue and ensuring this doesn’t happen in the future. Thank you for your understanding, The MailerSend team
06:00 UTC · resolved
This incident has been resolved.

Source

Feb 19, 20260mSEV 2

APP and API downtimeApp and API were down for an unstated period after a data migration; the update gives no scope, duration or region detail.AI-graded

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 2 · UNCLEAR · LOW CONFIDENCE
App and API were down for an unstated period after a data migration; the update gives no scope, duration or region detail.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

1 update

12:00 UTC · resolved
We had an unexpected downtime due to a data migration. It has been resolved, apologies for any inconvenience caused.

Source

Feb 19, 20260mSEV 3

We are experiencing a technical issueA faulty latest release disrupted the MailerSend app for some users starting 2022-11-15. The release was reverted, services were reported operational the next day, analytics stayed delayed, and the issue was resolved 2022-11-17. The text names no affected API components.AI-graded

Why this grade

RULES · SEV 1
Sev 1 from the incident title (no components listed)
CLAUDE · SEV 3 · UNCLEAR · LOW CONFIDENCE
A bad release broke the MailerSend app for some users for hours; the text does not say whether API sending was affected.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

8 updates

14:30 UTC · investigating
We are experiencing a technical issue in the MailerSend app that may affect some users. Our team is working to fix the issue as soon as possible. We will update the status page as it's resolved.
14:31 UTC · investigating
We detected the problem with our latest release and the team is investigating what is causing it. We will update our status page as soon as we have more information.
15:05 UTC · monitoring
We reverted our latest release and continue monitoring any performance degradation. The activity page might have some latencies. Our team is still investigating what is causing it.
18:17 UTC · monitoring
We are applying measures to stop any further issues.
00:12 UTC · monitoring
Services are operational and we are monitoring the situation.
10:22 UTC · monitoring
Analytics data is delayed at this time, our development team is working on a solution.
15:15 UTC · monitoring
We are working on a remedy, team will provide details at a later time.
08:31 UTC · resolved
The technical issue has been resolved. The App is back to normal. Thank you so much for your patience.

Source

Feb 19, 20260mSEV 2

Degraded performanceAPI performance was degraded for an unspecified period and scope; the provider gave no details on what broke or who was hit.AI-graded

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 2 · UNCLEAR · LOW CONFIDENCE
API performance was degraded for an unspecified period and scope; the provider gave no details on what broke or who was hit.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

2 updates

12:42 UTC · identified
The issue has been identified and a fix is being implemented.
13:36 UTC · resolved
This incident has been resolved.

Source

Feb 19, 20260mSEV 2

Backend server problemsOne backend database server went down; the update gives no duration or customer-facing impact, so the effect is unclear.AI-graded · one location

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 2 · LOCAL · LOW CONFIDENCE
One backend database server went down; the update gives no duration or customer-facing impact, so the effect is unclear.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

1 update

11:00 UTC · resolved
We had a downtime on one of our backend database servers. The problem has been fixed.

Source

Feb 19, 20260mSEV 1

Email activity dataProvider says all existing email activity data was lost; new activity logging works again after the fix. Counted as Sev 1 for data loss or exposure.AI-graded

Why this grade

RULES · SEV 1
Sev 1 because the provider reported data loss or exposure
CLAUDE · SEV 1 · UNCLEAR · MEDIUM CONFIDENCE · DATA LOSS
Provider says all existing email activity data was lost; new activity logging works again after the fix.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

1 update

13:00 UTC · resolved
We are sorry to inform you that all existing email activity data has been lost. All new data is in place, and email activity functionality works now. Please do contact our support if you need assistance.

Source

Feb 19, 20260mSEV 1

We experienced a technical issueA release caused an outage on MailerSend's sending servers, including the SMTP relay, and emails sent through it were lost. SMTP was reported operational about two hours later, and the incident was resolved in the late afternoon UTC. The text gives no further detail on the cause or the number of customers affected.AI-graded

Why this grade

RULES · SEV 1
Sev 1 from the incident title (no components listed)
CLAUDE · SEV 1 · UNCLEAR · MEDIUM CONFIDENCE · DATA LOSS
Sending servers and SMTP relay went down during a release, and emails sent through the relay were lost; scope not stated.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

3 updates

10:30 UTC · monitoring
We experienced a technical issue during our release, which caused an outage on our sending servers. Our engineers worked on a fix as soon as we identified the root cause. This incident happened at 10:36 am UTC+2 and resulted in losing emails sent with our SMTP relay. We apologize for this downtime. We know you have emails to deliver, so we have been 100% focused on resolving this and preventing future issues. You can check the status page for regular updates. We appreciate your understanding, The MailerSend team
12:45 UTC · monitoring
SMTP is now operational.
16:52 UTC · resolved
This incident has been resolved.

Source

Feb 19, 20260mSEV 2

Technical issue on our SMTP proxySome users failed to connect to the SMTP proxy for about 40 minutes because of a certificate problem causing TLS errors.AI-graded · some customers

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 2 · SUBSET · MEDIUM CONFIDENCE
Some users failed to connect to the SMTP proxy for about 40 minutes because of a certificate problem causing TLS errors.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

1 update

14:30 UTC · resolved
Some of our users experienced a service interruption today between 4:30 and 5:10pm (GMT+2) when connecting to our SMTP proxy. After investigation, we found out the certificate on our SMTP proxy caused some clients problems when connecting, resulting in TLS-related exceptions being reported. The issue has now been resolved. We sincerely apologize for the inconvenience. Thank you for your understanding, The MailerSend team

Source

Feb 19, 20260mSEV 2

We're experiencing a technical issue resulting in a 401 error increaseMailerSend's API returned 401 authentication errors to callers for about one hour on 25 October 2023, so requests that should have succeeded were rejected. The incident was resolved at 09:30 UTC with no cause given. Scope across customers was not stated.AI-graded

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 2 · UNCLEAR · MEDIUM CONFIDENCE
API calls returned spurious 401 errors for about an hour; the scope across customers is not stated.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

2 updates

08:30 UTC · investigating
We are experiencing a technical issue that might result in 401 errors while using the API. All of our engineers are working hard to fix the issue as soon as possible. We understand that you have emails to deliver and an apology will not mean much right now. But we wanted you to know that we are 100% focused on fixing the issue and ensuring this doesn’t happen in the future. Thank you for your understanding, The MailerSend team
09:30 UTC · resolved
The incident was solved. You should no longer receive 401 errors when calling the API.

Source

Feb 19, 20260mSEV 2

Delayed delivery timeEmail delivery was delayed for about 50 minutes due to unexpectedly high sending load; emails were still being sent.AI-graded

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 2 · UNCLEAR · MEDIUM CONFIDENCE
Email delivery was delayed for about 50 minutes due to unexpectedly high sending load; emails were still being sent.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

3 updates

10:43 UTC · identified
Due to an unexpectedly high sending load, we're experiencing some delays in email delivery. Emails are still being sent. This should return to normal in a few minutes.
10:49 UTC · identified
We are continuing to work on a fix for this issue.
11:28 UTC · resolved
The slowdown was absorbed.

Source

Feb 19, 20260mSEV 2

We've experience a technical issue on our bulk endpointA release on April 10 broke MailerSend's bulk-sending feature, which was down from 12:50 to 15:12 UTC. Rollback followed, but slowdowns continued. A hotfix with stricter retries shipped April 11 after another outage from 11:24 to 12:16 UTC, totalling about 3h14 of slowdown.AI-graded · one model or feature

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 2 · SINGLE · HIGH CONFIDENCE
The bulk-sending endpoint was down for about 2h22 on April 10 and 52 minutes on April 11; other endpoints were not described as affected.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

1 update

00:30 UTC · resolved
We experienced a technical issue that caused delays while using the bulk endpoint. The bulk-sending feature was down between 12:50 UTC and 15:12 UTC on April 10th and between 11:24 UTC and 12:16 UTC on April 11th. We released a new version of the app at 12:50 UTC, and then, 20 minutes after the release, we identified an error and started working on a fix. At 15:12 UTC, we decided to revert to the last stable version. Around 15:58 UTC, the slowdown in the bulk sending was identified, and we started investigating. We had an unusual high load, which was slowing down the sending. At 11:24 the next day, we released a hotfix to handle this larger load by implementing a stricter retry mechanism. This amounts to 3h14 of slowdown. We understand that you have emails to deliver and an apology will not mean much right now. But we wanted you to know that we are 100% focused on fixing all issues and ensuring this doesn’t happen in the future. Thank you for your understanding, The MailerSend team

Source

Feb 19, 20260mSEV 2

We are experiencing a technical issueBulk and single email sending slowed for a few accounts for about two hours. Emails were queued and still sent, but delivered events lagged. Cause was a memory leak on sending servers, fixed by a restart. A more scalable sending infrastructure is planned to prevent recurrence.AI-graded · some customers

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 2 · SUBSET · MEDIUM CONFIDENCE
Email sending through the bulk and single send endpoints was slowed for a few accounts for about 2 hours, with delivered events delayed.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

4 updates

16:00 UTC · investigating
We are experiencing a technical issue with bulk sending that cause a delay in email sending. Our engineers are working hard to resolve the issue within the next couple of hours. We appreciate your patience.
17:31 UTC · investigating
We are continuing to investigate the issue. The /email endpoint is also showing signs of delayed sending. Emails are queued and sent, but the delivered event is being delayed.
18:07 UTC · resolved
The technical issue has been resolved. The email sending are back to normal. Thank you so much for your patience.
18:17 UTC · resolved
We experienced slowdowns in sendings, on our single and bulk email endpoints. This affected a few accounts for around 2 hours. Our team investigated the issue and found that our sending servers had a memory leak. After the restart, the slowdowns were reduced, and the speed of sending went back to normal. For the past few weeks, we have been working on a more scalable sending infrastructure, and we plan to roll it out this week. This will address these problems so they do not happen again. We understand you have emails to deliver, and an apology will not mean much right now. We wanted to be transparent and let you know that we are 100% focused on fixing the issue and improving our product. Thank you for your understanding, The MailerSend team

Source

Feb 19, 20260mSEV 2

Email delivery and activity status problemsSome MailerSend users saw delayed email sending between 08:00 and 12:00 UTC, and the activity reporting system may have shown inaccurate information. The provider deployed several fixes but did not name a root cause. No component was listed and no impact label was given.AI-graded · some customers

Why this grade

RULES · SEV 3
Sev 3 from the incident title (no components listed)
CLAUDE · SEV 2 · SUBSET · MEDIUM CONFIDENCE
Email sending was delayed for some users and activity reporting was inaccurate for about four hours; the text does not give a wider scope.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

1 update

08:00 UTC · resolved
Today, we encountered technical challenges that led to delays in email delivery and discrepancies in activity reporting. Specifically, between 08:00 UTC and 12:00 UTC, some users may have experienced delays in sending emails, and our activity reporting system may have provided inaccurate information. Upon identifying these issues, our team immediately sprung into action and we deployed multiple solutions to fix said problems. We understand the frustration and inconvenience that delayed email delivery and inaccurately reported activity statuses can cause, especially when you rely on our platform for important communications. We want to sincerely apologize for the recent disruptions you may have experienced. An apology may not mean much, but please know that our entire team is committed to preventing similar incidents in the future.

Source

Feb 19, 20260mSEV 4

Mail transfer agent delivery report delayBetween May 18 05:15 UTC and May 19 16:05 UTC, some users saw delayed email activity reporting and wrong timestamps on delivered statuses, caused by a mail transfer agent delivery report delay. Email delivery was not impacted.AI-graded

Why this grade

RULES · SEV 2
Sev 2 from the incident title (no components listed)
CLAUDE · SEV 4 · UNCLEAR · MEDIUM CONFIDENCE
Email activity reporting and delivered-status timestamps were delayed or inaccurate for some users; email delivery itself was not affected.
Claude Haiku 5.5 · prompt v8 · Oct 23, 2026 · Raw record

1 update

14:00 UTC · resolved
We have recently encountered technical difficulties that have affected the accuracy of email activity reporting within our platform. Between May 18 05:15 UTC to May 19 16:05 UTC, some users may have experienced delayed email activity reporting and inaccuracies in the timestamp on delivered activity statuses. Upon thorough investigation, we have determined that these issues stemmed from our mail transfer agent delivery report delay (email delivery was not impacted). This unforeseen challenge resulted in disruptions to our usual service standards, for which we sincerely apologize. We understand the importance of timely and accurate email communication for your operations, and we recognize the impact that these issues may have had on your experience. Please know that addressing these challenges is our top priority, and we believe that we have diligently worked towards resolving this. Your trust in our service means everything to us, and we are committed to earning back your confidence by delivering the dependable performance you expect and deserve. Should you have any questions or concerns, please do not hesitate to reach out to our support team. We are here to assist you in any way we can.

Source