Microsoft actively blocking DO IP range

Mail sent from my droplet is being returned when the recipient is MSN, Outlook or Hotmail

Mail.log excerpt;

Mar 25 19:40:58 box postfix/qmgr[4566]: 4AFDA2036C: from=<>, size=1477, nrcpt=1 (queue active) Mar 25 19:40:58 box postfix/submission/smtpd[28496]: disconnect from localhost[] Mar 25 19:40:58 box postfix/smtp[28928]: 4AFDA2036C:,[]:25, delay=0.67, delays=0.09/0/0.43/0.14, dsn=5.7.1, status=bounced (host[] said: 550 5.7.1 Unfortunately, messages from [] 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 [] (in reply to MAIL FROM command)) Mar 25 19:40:58 box postfix/smtp[28928]: 4AFDA2036C: lost connection with[] while sending RCPT TO Mar 25 19:40:58 box postfix/bounce[28974]: 4AFDA2036C: sender non-delivery notification: F003928C01 Mar 25 19:40:58 box postfix/qmgr[4566]: 4AFDA2036C: removed

(I redacted the source domain and destination email ----------)

I have contacted DO support and they just say maintaining reputation is hard for them and to try changing regions or using a third party to relay email.

Anyone have practical experience of this issue and how to get around it.

I have a bunch of users that are seriously unhappy at the moment!

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As far as I know, Mailgun is of no use for general mail services, eg sending SMTP from a mail server (including attachments) - its just for transactional email?

As DO mentioned, try an external service, you can use Mailgun for it, it works nicely

Something else I have found with Microsoft is they also look to see if the PTR Records are present for the server. I have run into the issue with most cloud providers including Azure and AWS.

Here is another discussion that touches on this topic…