<![CDATA[Mailserver does not deliver to certain email addresses]]>Using the built in SMTP, I have set up a mailing list with 10 external email addresses. All but two do receive the mails.

Of the two that do not, one is on @t-online and one is on @hotmail.com/@outlook.com. And both are the only ones on those two services.

Both do not get the mails at all, they are not in spam.

What am I doing wrong? Is there a way to trace the mails?

]]>https://forum.cloudron.io/topic/4964/mailserver-does-not-deliver-to-certain-email-addressesRSS for NodeTue, 16 Jun 2026 06:20:52 GMTSat, 24 Apr 2021 09:44:09 GMT60<![CDATA[Reply to Mailserver does not deliver to certain email addresses on Tue, 25 May 2021 09:26:35 GMT]]>I end this thread because I now have a more specific one going.

]]>https://forum.cloudron.io/post/31850https://forum.cloudron.io/post/31850Tue, 25 May 2021 09:26:35 GMT<![CDATA[Reply to Mailserver does not deliver to certain email addresses on Sat, 22 May 2021 06:55:55 GMT]]>@humptydumpty thank you very much.

Here my result and their system reply:

The IP address in question is not currently blocked in our system. Please refer to the email message you received from Microsoft and follow the steps it suggests.

If you're trying to delist an IP address blocked in Hotmail.com/Live.com/Outlook.com, please use the following link.
https://support.microsoft.com/en-us/getsupport?oaspworkflow=start_1.0.0.0&LINK-EDITED

If you're trying to delist a banned or blocked sender, please open a support ticket from your tenant.

]]>https://forum.cloudron.io/post/31766https://forum.cloudron.io/post/31766Sat, 22 May 2021 06:55:55 GMT<![CDATA[Reply to Mailserver does not deliver to certain email addresses on Tue, 04 May 2021 13:11:42 GMT]]>The SNDS page/service is useless. It's good to tell if you're blocked or not and that's it. I signed up and added my server IP +8 months ago and I have yet to receive a single report from them. Anyway, I found the right page to apply for delisting if your IP is blocked: https://sender.office.com.

]]>https://forum.cloudron.io/post/30770https://forum.cloudron.io/post/30770Tue, 04 May 2021 13:11:42 GMT<![CDATA[Reply to Mailserver does not deliver to certain email addresses on Mon, 03 May 2021 00:49:29 GMT]]>Just ran across this tool: https://www.mail-tester.com

Could be super helpful for folks.

https://answers.microsoft.com/en-us/outlook_com/forum/all/how-to-request-to-whitelist-a-domain-on-microsoft/3b6e2b4c-32e9-4e76-af38-dd0982e526b6

Has good info on solving Microsoft specific problems.

]]>https://forum.cloudron.io/post/30674https://forum.cloudron.io/post/30674Mon, 03 May 2021 00:49:29 GMT<![CDATA[Reply to Mailserver does not deliver to certain email addresses on Mon, 26 Apr 2021 19:34:31 GMT]]>Sometimes the only way to overcome IP limitation is https://docs.cloudron.io/email/#relay-outbound-mails . But IIRC outlook atleast has a form you can fill up to get your IP/domain whitelisted (they send you an email that you have to click).

]]>https://forum.cloudron.io/post/30402https://forum.cloudron.io/post/30402Mon, 26 Apr 2021 19:34:31 GMT<![CDATA[Reply to Mailserver does not deliver to certain email addresses on Mon, 26 Apr 2021 08:47:00 GMT]]>@andxclfor IP reputation is becoming increasingly important for mail delivery and both T-Online and Microsoft have implemented quite aggressive checks. If your domain starts sending mail from a new IP, for example, there is a good chance it will initially be blocked. You should get an undeliverable error in such cases though. From experience I can say that T-Online have been very quick to rectify this.

]]>https://forum.cloudron.io/post/30370https://forum.cloudron.io/post/30370Mon, 26 Apr 2021 08:47:00 GMT<![CDATA[Reply to Mailserver does not deliver to certain email addresses on Mon, 26 Apr 2021 06:22:34 GMT]]>Turns out that my IP is spam. Taking it up with DigitalOcean.

Thank you all!

]]>https://forum.cloudron.io/post/30367https://forum.cloudron.io/post/30367Mon, 26 Apr 2021 06:22:34 GMT<![CDATA[Reply to Mailserver does not deliver to certain email addresses on Mon, 26 Apr 2021 05:48:00 GMT]]>@moonmeister Thank you. And what did you do? Change IP?

]]>https://forum.cloudron.io/post/30365https://forum.cloudron.io/post/30365Mon, 26 Apr 2021 05:48:00 GMT<![CDATA[Reply to Mailserver does not deliver to certain email addresses on Sun, 25 Apr 2021 02:59:46 GMT]]>@andxclfor I've run into this as well. Though I get an undeliverable error usually. Basically, Microsoft uses a very broad blacklist that adds entire subnets to the list if there is one bad actor on the subnet. So I get blocked because someone else on DO is being bad.

]]>https://forum.cloudron.io/post/30350https://forum.cloudron.io/post/30350Sun, 25 Apr 2021 02:59:46 GMT<![CDATA[Reply to Mailserver does not deliver to certain email addresses on Sat, 24 Apr 2021 10:05:35 GMT]]>At least for the hotmail/outlook addresses, you can check out SNDS - https://sendersupport.olc.protection.outlook.com/snds/index.aspx - to verify status and/or request unblocking if you're currently being blocked.

]]>https://forum.cloudron.io/post/30332https://forum.cloudron.io/post/30332Sat, 24 Apr 2021 10:05:35 GMT