Heysender Outage History

Started Sep 04, 2026, 12:00 PM UTC· resolved Sep 04, 2026, 01:20 PM UTC

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.

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Started Aug 10, 2026, 10:13 AM UTC· resolved Aug 10, 2026, 02:55 PM UTC

1. investigating Aug 10, 2026, 10:13 AM UTC

   We're currently experiencing issues sending e-mails from our system. We're investigating the cause..

2. resolved Aug 10, 2026, 02:55 PM UTC

   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..

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Started Apr 16, 2026, 05:00 PM UTC· resolved Aug 10, 2026, 03:02 PM UTC

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.

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Started Apr 16, 2026, 05:00 PM UTC· resolved Apr 16, 2026, 08:19 PM UTC

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..

5. resolved Apr 16, 2026, 08:19 PM UTC

   This incident has been resolved..

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Started Dec 11, 2025, 11:54 AM UTC· resolved Dec 11, 2025, 12:05 PM UTC

1. investigating Dec 11, 2025, 11:54 AM UTC

   All systems are down. We are currently investigating this incident..

2. resolved Dec 11, 2025, 12:05 PM UTC

   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..

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Started Dec 04, 2025, 06:01 AM UTC· resolved Dec 04, 2025, 01:09 PM UTC

1. investigating Dec 04, 2025, 06:01 AM UTC

   We're currently investigating what seems to be an issue connecting to smtp.heysender.com. New status within 30 minutes..

2. investigating Dec 04, 2025, 06:05 AM UTC

   The issue also affects the app, API and outgoing SMTP. We're still investigating..

3. resolved Dec 04, 2025, 06:11 AM UTC

   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..

4. resolved Dec 04, 2025, 01:09 PM UTC

   This incident has been resolved..

5. monitoring Dec 04, 2025, 01:11 PM UTC

   The issue was caused by a firewall issue at our hosting provider. It was solved with 10 minutes of total downtime to the system. .

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Started Oct 07, 2025, 09:29 AM UTC· resolved Oct 07, 2025, 10:20 AM UTC

1. investigating Oct 07, 2025, 09:29 AM UTC

   We're changing our S3 provider due to ongoing issues with the current solution. This has some consequences for our clients. We will be moving to our secondary hosting provider, Leaseweb Amsterdam, who already hosts the server sending out emails. This means that it will not impact any existing or future Data Protection Agreements. Since we store copies of HTML and text content as well as attachments in S3 the move means that this data can not be accessed until we have moved all historic data from our old provider to Leaseweb. This will take some time - we do not know how long yet since our current provider is having performance issues. Thus, we have disabled the resend function in Heysender which makes it possible to resend an email to a recipient. Since we can not access the content of the email we can not resend it. We apologise for any inconveniene caused. Get in touch with support if you have any questions..

2. resolved Oct 07, 2025, 10:20 AM UTC

   This incident has been resolved..

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Started Oct 02, 2025, 12:14 PM UTC· resolved Oct 03, 2025, 09:20 AM UTC

1. identified Oct 02, 2025, 12:14 PM UTC

   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..

2. monitoring Oct 02, 2025, 12:40 PM UTC

   We're sending emails again but we're not storing HTML and text content or attachments. We'll update when this changes..

3. resolved Oct 03, 2025, 09:20 AM UTC

   All services are back to normal. We are in touch with our provider about how to solve this issue for good..

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Started Sep 26, 2025, 06:53 PM UTC· resolved Sep 29, 2025, 08:30 AM UTC

1. investigating Sep 26, 2025, 06:53 PM UTC

   Due to an issue with our hosting provider's S3 storage we're currently experiencing difficulties accepting incoming SMTP and API connections. We're looking into solutions. New status will follow in 20 minutes..

2. identified Sep 26, 2025, 07:10 PM UTC

   We're working on bypassing S3 storage to get all systems running again. We will update again within the next 20 minutes..

3. identified Sep 26, 2025, 07:30 PM UTC

   S3 has been bypassed. We're running final tests before opening the system externally. We will update again within the next 20 minutes..

4. monitoring Sep 26, 2025, 08:45 PM UTC

   We're sending emails again. We have bypassed S3 storage which we use to save HTML content, text content and attachments of sent emails. For now these will not be saved to log and will not be available for lookup in the interface. As soon as S3 storage runs again we will re-enable it. We apologise sincerely for the issues this has caused. If you have any questions do not hestitate to contact support..

5. monitoring Sep 27, 2025, 08:10 AM UTC

   Our hosting provider is still working on bringing their S3 storage back up. We're sending emails without issues but we're still not logging all data due to S3 storage being offline. We will update here when we're actively logging everything again..

6. monitoring Sep 27, 2025, 04:11 PM UTC

   We're sending emails without issues but we're still not logging HTML and text content or attachments. We have decided to let everything stabilise so on Monday we will bring everything back to working order..

7. resolved Sep 29, 2025, 08:30 AM UTC

   All systems are running as expected. We're marking this as fixed..

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Started Jan 15, 2025, 07:45 PM UTC· resolved Jan 15, 2025, 07:45 PM UTC

No vendor updates were posted for this incident.

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Started Jan 07, 2025, 01:51 PM UTC· resolved Jan 07, 2025, 02:03 PM UTC

1. monitoring Jan 07, 2025, 01:51 PM UTC

   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..

2. resolved Jan 07, 2025, 02:03 PM UTC

   This incident has been resolved..

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Started Dec 19, 2024, 12:03 PM UTC· resolved Dec 19, 2024, 12:28 PM UTC

1. monitoring Dec 19, 2024, 12:03 PM UTC

   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..

2. resolved Dec 19, 2024, 12:28 PM UTC

   This incident has been resolved..

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