Heysender Outage History

Heysender is up right now

Heysender had 13 outages in the last 2 years totaling 2783h 21m of downtime — averaging 0.5 incidents per month.

There were 13 Heysender outages since December 19, 2024 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 →

Minor October 2, 2025

S3 issues again

Detected by Pingoru
Oct 02, 2025, 12:14 PM UTC
Resolved
Oct 02, 2025, 12:14 PM UTC
Duration
—
Timeline · 1 update
  1. resolved Oct 02, 2025, 12:14 PM UTC

    Type: Incident Duration: 21 hours and 6 minutes Affected Components: API, App Oct 2, 12:14:00 GMT+0 - Identified - Once again our hosting provider has issues with S3 hosting. We are making changes in order to handle the issue but mail queues should be up and running again soon. New update in 20 minutes. Oct 2, 12:40:00 GMT+0 - Monitoring - We're sending emails again but we're not storing HTML and text content or attachments. We'll update when this changes. Oct 3, 09:20:00 GMT+0 - Resolved - All services are back to normal. We are in touch with our provider about how to solve this issue for good.

Read the full incident report →

Minor January 15, 2025

Planned downtime January 21st 2025

Detected by Pingoru
Jan 15, 2025, 07:45 PM UTC
Resolved
Jan 15, 2025, 07:45 PM UTC
Duration
—
Timeline · 1 update
  1. resolved Jan 15, 2025, 07:45 PM UTC

    Type: Maintenance Duration: 2 hours Affected Components: API, Incoming SMTP, App, Outgoing SMTP Jan 15, 19:45:00 GMT+0 - Identified - We will be updating a central piece of SMTP software in Heysender. This will result in a downtime on the incoming SMTP service lasting a few minutes where the SMTP service will not respond to connection requests. Afterwards, the incoming SMTP service will be running but all outgoing e-mail will be caught and saved for later delivery while we update the software. The date and time of the update is: **Tuesday 21st of January 2025 from 20:45 CET to 22:45 CET** We expect the entire process to take 1-2 hours from start to end. For the first few minutes no incoming SMTP requests will succeed and afterwards there will be a delay of up to 2 hours on outgoing e-mail. If you have any questions regarding the update please do not hesitate to get in touch with support. Jan 15, 21:45:00 GMT+0 - Completed - Maintenance has completed successfully.

Read the full incident report →

Minor January 7, 2025

Issue with logging

Detected by Pingoru
Jan 07, 2025, 01:51 PM UTC
Resolved
Jan 07, 2025, 01:51 PM UTC
Duration
—
Timeline · 1 update
  1. resolved Jan 07, 2025, 01:51 PM UTC

    Type: Incident Duration: 12 minutes Affected Components: API, Incoming SMTP, App, Outgoing SMTP Jan 7, 13:51:00 GMT+0 - Monitoring - We are currently experiencing e-mails with logging in Heysender. Our hosting partner is updating a key part of their infrastructure which we use to store log files making us unable to handle the logs. We have made a change to the system so we bypass logging of text and HTML versions which solves the issue for now. We will update when all is back to normal. Jan 7, 14:03:00 GMT+0 - Resolved - This incident has been resolved.

Read the full incident report →

Minor December 19, 2024

Issue with webhooks

Detected by Pingoru
Dec 19, 2024, 12:03 PM UTC
Resolved
Dec 19, 2024, 12:03 PM UTC
Duration
—
Timeline · 1 update
  1. resolved Dec 19, 2024, 12:03 PM UTC

    Type: Incident Duration: 15 days, 21 hours and 25 minutes Dec 19, 12:28:00 GMT+0 - Resolved - This incident has been resolved. Dec 19, 12:03:00 GMT+0 - Monitoring - Due to a change in the service some webhooks changed format. This has resulted in issues with integrations parsing the webhooks. The change has been rolled back and we're working on fixing the format before we retry the webhooks with the right format. If your service responds with 200 OK when a webhook is received we will not retry the webhook. Get in touch with support if you need assistance receiving the webhooks again.

Read the full incident report →