Outlook - Undelivered Mail Returned to Sender



I just tried to send an email to a hotmail address and got this?

 hotmail-com.olc.protection.outlook.com[XXX] said: 550 5.7.1
Unfortunately, messages from [XXX] weren't sent. Please contact
your Internet service provider since part of their network is on our block
list (AS3140). You can also refer your provider to
[SN1NAM02FT052.eop-nam02.prod.protection.outlook.com] (in reply to MAIL
FROM command)

I signed up to snds program by microsoft, and it does seem like that address is in their block list. But I did manage to send an email to hotmail a week ago.

There’s only been a few test emails sent by this host, and no other users. I guess it’s some other digital ocean spammers on this address range? Is this common?

All the various tests I could do for email passed, and sending to other hosts report no issues.


Looks like your VPS providers IP Address’s are blocked, I would talk to them first. It’s pretty common to happen to VPS providers, what I would do is contact Digital Ocean and get them to unblock the IP’s from Microsoft.

Or you could get a dedicated server like from nocix.net.(As an example) which will give you IP’s instead of sharing a whole block.


Ok, thanks a lot for your reply. I reported it to them. Fingers crossed!

I guess I should consider a dedicated server then.



I have been with nocix.net (US based) for over 4 years now. They work great, simple and cheap. and full control over what I use them for. Never had an issue with IP Block blacklisting with them, but results will vary.

Good luck!