Author Archive for Mads Petersen

Migration postponed for 24 hours..

Posted on: March 23rd, 2026 by

As you can read in the update of the previous post on this blog, we ran into some unforeseen DNS issues during the migration, and were able to stop the actual migration in time. We found what we believe is the cause of the issues, and made changes to the configurations that we need to test.

At  the time of writing, we have postpone the migration until:

Tuesday March 24, 2026 @ 13:00 CET.

As it was the plan today, at 13:00 CET we will switch over the database and the main DNS.

This will cause downtime that can last up to 20 – 30 minutes.

We sincerely apologize for the inconvenience

Update 2026-03-24 @ 13:00 CET: The DNS issues from yesterday is under control. We are doing it. The migration is in progress.

Update 2026-03-24 @ 14:20 CET: The database has been migrated to the new environment. we are now updating the DNS. When DNS is updated, we can just wait for the global update. depending on where you are on the globe, this can take anywhere from a few minutes to 72 hours (just to mention the extremes). 

Update 2026-03-24 @ 15:30 CET: The migration has finished and all data is live on the new environment. We however hit a few issues; one certificate issue, one webclient defect, and DNS is slow to propagate in some areas (we know from user feedback). These issues should be resolved by now. At this time we are investigating some delays, but mail is flowing and getting delivered. Most of the issues are coming down to “restarting a browser or a Thunderbird”, but we resolve the tickets in Support as they come in. If you have issues that you do not read about here, then please contact Support.

 

Tags: , , ,

Final migration date and a new feature..

Posted on: March 12th, 2026 by

Final Migration date

As we get closer to the migration and we get ready, we now with confidence can set the actual final date for the migration to the new environment on the new hardware. The migration is going to happen on:

Monday 23rd of March 2026.

All systems are running well and our tests are successful. We are looking forward to using the new system.

> Continue Reading

Tags: , , ,

Incident report: Spam attack.. [Updated]

Posted on: March 6th, 2026 by

On Tuesday 2026-03-03, a number of user accounts on Kolab Now was used to send out large amounts of spam. The spammers didn’t get to send out much mail. Most of it was stopped in the Kolab Now exit filtering, but the spam rating of the mails going out unfortunately was high and caused Microsoft online services, specifically outlook.com, hotmail.com, to add two of the Kolab Now exit IP addresses to their block lists. This caused emails sent to recipients on these services to bounce with messages like:

550 5.7.1 Unfortunately, messages from [212.103.80.154] weren’t sent.

Please contact your Internet service provider since part of their network is on our block list (S3150).

The spammers were identified and stopped, but the damage was done.

> Continue Reading

Tags: , , , ,

What’s going on?

Posted on: February 13th, 2026 by

It is Friday..

..and it is time to give you a short update on something that we have been working on for a while.

Kolab Now is running on high-end equipment located in a data-center in Bern, Switzerland. It is running the Email- and Groupware services for our customers, such as you. Where as we are aware that Email is ‘mission critical’ for our users, we do what we can to keep the service stable and alive 24/7.

> Continue Reading

Tags: , , , , ,

Transparency reporting..

Posted on: January 13th, 2026 by

For the sake of transparency we used to report on our interactions with authorities every year. Unfortunately we have missed a few of those reports. Some users missed such updates, and , not only for those users, but also according to our terms of service, and for the sake of transparency, we want to restart this good routine. This post is the transparency reporting for the year 2025.

> Continue Reading

Tags:

Incident report: IMAP client service temporarily unstable..

Posted on: November 20th, 2025 by

Last night at 21:50 UTC a large number of client connections hit Kolab Now, which resulted in the IMAP client servers (‘imap.kolabnow.com’) running out of memory. Staff was noted about the issue at 06:00 UTC, and immediately raised the amount of memory for these servers, which brought the issue to an end.

During these ~8 hours users of IMAP clients had issues with unstable connections; some might even have been completely unable to connect.

Mail transport was not impacted. all mails were streaming in and out as they should, and also the webclient (‘https://kolabnow.com/apps’) worked well during the period.

The issue was the unusually large number of incoming client connections. To mitigate the situation and avoid similar issues, the staff has enlarged the memory size on the servers in question, and are now working to improve the monitoring of the service.

We regret the incident and apologize for any inconvenience that this may have caused.

 

Tags: ,

Incident report: 50% of ActiveSync connections failed..

Posted on: June 17th, 2025 by

On Sunday 2025-06-15 one of the Kolab now ActiveSync servers were getting overloaded and got stuck on failed jobs. In turn, about 50% of the ActiveSync jobs were failing – leading to some ActiveSync users loosing the connections to Outlook or to their mobile devices.

> Continue Reading

Tags: ,

Incident report: Some mails to Microsoft online services was getting blocked..

Posted on: May 7th, 2025 by

Yesterday we dealt with a spammer/phisher who specifically targeted the Microsoft outlook.com service (and it’s affiliates).  One of the Kolab Now MX servers was listed on the Microsoft throttle list (S3150). This meant that some users saw, that mails sent to recipients at ‘@outlook.com’, ‘@live.com’, ‘@hotmail.com’, and other Microsoft online services was bounced back.

> Continue Reading

Tags: , , ,

Incident report: Some mails to Microsoft online services was getting blocked..

Posted on: February 13th, 2025 by

This afternoon earlier today one of the Kolab Now MX servers was listed on the Microsoft block list. This means that some users might have seen, that mails sent to recipients at ‘@outlook.com’, ‘@live.com’, ‘@hotmail.com’, and other Microsoft online services was bounced back with the message that looks something like this:

This is the mail system at host mx.kolabnow.com. 
I'm sorry to have to inform you that your message could not 
be delivered to one or more recipients. It's attached below. 
For further assistance, please send mail to postmaster. 
If you do so, please include this problem report. You can 
delete your own text from the attached returned message. 
The mail system <some-email@outlook.com>: host  
outlook-com.olc.protection.outlook.com[x.x.x.x] said: 550 5.7.1 
Unfortunately, messages from [y.y.y.y] weren't sent. Please contact 
your Internet service provider since part of their network is on our block 
list (S3150). You can also refer your provider to 
http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol 
Filter Agent][AGT=PFA][MxId=<some long number>] 
[SG2PEPF03345FBECA.apcprd05.prod.outlook.com 2025-02-13T<timestamp>Z 
<another long number>] (in reply to MAIL FROM command)

Although the listing was fast discovered, Microsoft was contacted and the listing is reversed as soon as it is possible, it took a while. At this time emails should be delivered to the Microsoft online services.

A few users has misinterpreted the symptoms with error messages from missing the DKIM changes made on Monday (please read this blog post from December 2024 and the follow ups). If you are a group manager, then please make sure that you have the new DKIM related CNAMES added to your DNS zone.

If you have any questions or concerns in this context, then please contact support.

Tags: , , , , , , ,