In ubuntu, I'm using postfix and dovecot to deliver email from my server.

I've set DKIM, SPF and all other stuff. I have my email tested from https://www.mail-tester.com and got 10/10 point.

When I'm sendin an e-mail to

  • Gmail - it is sent and the result is like the following:

to=emailaddress@gmail.com, relay=gmail-smtp-in.l.google.com[]:25, delay=0.5, delays=0.08/0.01/0.15/0.27, dsn=2.0.0, status=sent (250 2.0.0 OK

  • Outlook - it is not sent and the result is like the following:

to=emailaddress@hotmail.com, relay=eur.olc.protection.outlook.com[]:25, delay=0.14, delays=0.07/0/0.06/0.02, dsn=5.7.1, status=bounced (host eur.olc.protection.outlook.com

lost connection with eur.olc.protection.outlook.com[] while sending RCPT TO

What possible problem could it be that it can't deliver Outlook while it can deliver to Gmail?

I'll be appriciated for your answers.

(If you need any further information to understand the problem please let me know in the comments.. Thank you)

  • The error message reproduced seems to be incomplete. Nonetheless, just because Google accept a message does not mean Microsoft will. They operate different spam blockers and the algorithms are not revealed to the public. Microsoft are known to more aggressively reject/drop mail they consider as likely spam.
    – tater
    Dec 27, 2020 at 21:50

1 Answer 1


Do you encounter the same issue if you send emails from other email addresses(e.g. Gmail/Outlook/Office365/etc.) to this hotmail mailbox?

If emails from other email servers don't reach to the hotmail mailbox, I guess that the destination receive server configured some restrictions for it(e.g. Black List, rules etc.). If only your email server couldn't send to the hotmail mailbox, please check if there is any recipient restriction configured, the following links about SMTP access restriction lists and similar issues are for your reference:

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