Heysender Outage History

Heysender is up right now

Heysender had 8 outages in the last 2 years totaling 2783h 21m of downtime — averaging 0.3 incidents per month.

There were 8 Heysender outages since October 7, 2025 totaling 2783h 21m of downtime. Each is summarised below — incident details, duration, and resolution information.

Source: https://status.heysender.com

Minor September 4, 2026

Microsoft has issues receiving email

Detected by Pingoru
Sep 04, 2026, 12:00 PM UTC
Resolved
Sep 04, 2026, 01:20 PM UTC
Duration
1h 19m
Affected: Outgoing SMTP
Timeline · 2 updates
  1. monitoring Sep 04, 2026, 12:00 PM UTC

    Since 9:50 CEST this morning Microsoft has had issues receiving email. This means that many emails sent to Office365 recipients will result in a soft bounce with this message: 52.101.68.10 failed after I sent the message./Remote host said: 451 4.7.500 Server busy. Please try again later from \[REDACTED\]. (S77714) \[[DB1PEPF000509E3.eurprd03.prod.outlook.com](http://DB1PEPF000509E3.eurprd03.prod.outlook.com) 2026-09-04T08:16:36.825Z 08DF04AEA47F75BA\]/ If you have access to the Office365 admin page they have created an issue to follow here: We're monitoring the issue but for now there is nothing we can do to force emails through. Emails sent during Microsoft downtime will be tried again for the following 48 hours until delivery is possible. (We're mainly creating this issue to have a place to point clients to for updates. There is nothing we can do inhouse to solve the issue.)

  2. resolved Sep 04, 2026, 01:20 PM UTC

    This incident has been resolved by Microsoft. We're working on emptying the queues and we expect all email to be delivered soon.

Read the full incident report →

Minor September 1, 2026

Planned disruption 1st of September

Detected by Pingoru
Sep 01, 2026, 08:45 AM UTC
Resolved
Sep 01, 2026, 08:45 AM UTC
Duration
—
Timeline · 1 update
  1. resolved Sep 01, 2026, 08:45 AM UTC

    Type: Maintenance Duration: 26 minutes Affected Components: Incoming SMTP, API Sep 1, 08:45:01 GMT+0 - Identified - Maintenance is now in progress Sep 1, 09:11:10 GMT+0 - Completed - Maintenance has completed successfully. Aug 28, 13:15:43 GMT+0 - Identified - We are planning for a scheduled maintenance on the 1st of September during working hours. The specific time will be added to this case when we have it. During the maintenance you might experience delays in connecting to our SMTP and API service but the delay should be no longer than a few seconds. Aug 31, 12:23:13 GMT+0 - Identified - We will be running the maintenance between 10:45 am and 11:15 am tomorrow.

Read the full incident report →

Minor August 10, 2026

Issues with sending.

Detected by Pingoru
Aug 10, 2026, 10:13 AM UTC
Resolved
Aug 10, 2026, 10:13 AM UTC
Duration
—
Timeline · 1 update
  1. resolved Aug 10, 2026, 10:13 AM UTC

    Type: Incident Duration: 4 hours and 42 minutes Affected Components: Outgoing SMTP, API Aug 10, 10:13:00 GMT+0 - Investigating - We're currently experiencing issues sending e-mails from our system. We're investigating the cause. Aug 10, 14:55:12 GMT+0 - Resolved - Due to an issue with our hosting provider Heysender could not send email for a few hours this afternoon. The issue has been solved and we're monitoring the state of the service for the rest of the day.

Read the full incident report →

Major April 16, 2026

Issues with events

Detected by Pingoru
Apr 16, 2026, 05:00 PM UTC
Resolved
Aug 10, 2026, 03:02 PM UTC
Duration
115d 22h
Affected: heysenderApp
Timeline · 4 updates
  1. investigating Apr 16, 2026, 05:00 PM UTC

    We are currently investigating an issue resulting in events not being registered correctly. Emails are leaving the servers but the response is not saved correctly. We'll update when we know more.

  2. identified Apr 16, 2026, 05:53 PM UTC

    We have identified the root of the issue and are mitigating it now.

  3. monitoring Apr 16, 2026, 06:00 PM UTC

    We implemented a fix and are currently monitoring the result. The root cause is once again our Object Storage solution which broke. We have switched over to our secondary provider. This means that preview of emails sent before this update will not work as well as the resend functionality. We expect to solve these issues over the next couple of days but for now we are monitoring to ensure everything works as intended.

  4. monitoring Apr 16, 2026, 06:19 PM UTC

    Outgoing traffic sent while the issue persisted will have been delayed but started being sent when we implemented the fix.

Read the full incident report →

Minor December 11, 2025

Unexpected downtime

Detected by Pingoru
Dec 11, 2025, 11:54 AM UTC
Resolved
Dec 11, 2025, 11:54 AM UTC
Duration
—
Timeline · 1 update
  1. resolved Dec 11, 2025, 11:54 AM UTC

    Type: Incident Duration: 11 minutes Affected Components: Incoming SMTP, Outgoing SMTP, App, API Dec 11, 11:54:20 GMT+0 - Investigating - All systems are down. We are currently investigating this incident. Dec 11, 12:05:39 GMT+0 - Resolved - We're back online and all systems are operational. Many apologies for the issues - we're working closely with our service provider to avoid similar incidents going forward.

Read the full incident report →

Minor December 4, 2025

Connection issues to smtp.heysender.com

Detected by Pingoru
Dec 04, 2025, 06:01 AM UTC
Resolved
Dec 04, 2025, 06:01 AM UTC
Duration
—
Timeline · 1 update
  1. resolved Dec 04, 2025, 06:01 AM UTC

    Type: Incident Duration: 9 hours and 46 minutes Affected Components: Incoming SMTP, Outgoing SMTP, API, App Dec 4, 13:09:17 GMT+0 - Resolved - This incident has been resolved. Dec 4, 06:11:19 GMT+0 - Resolved - All systems seem to be online again. We're keeping an eye on things but from here it seems to be a network issue at our hosting supplier resulting in about 10 minutes of downtime. We will update when we know more. Dec 4, 13:11:11 GMT+0 - Postmortem - The issue was caused by a firewall issue at our hosting provider. It was solved with 10 minutes of total downtime to the system. Dec 4, 06:01:33 GMT+0 - Investigating - We're currently investigating what seems to be an issue connecting to smtp.heysender.com. New status within 30 minutes. Dec 4, 06:05:04 GMT+0 - Investigating - The issue also affects the app, API and outgoing SMTP. We're still investigating.

Read the full incident report →