My mail hosting provider rejects test email relayed from postfix on FQDN-less host, but thunderbird ok

Adam asked:

When I send mail with Thunderbird via my mail hosting provider, there’s no problem. However I set up postfix in the usual way so that it functions as a send-only SMTP server on my DHCP client with no FQDN, but it fails to send.

postfix/pickup[21225]: 264F118807D3: uid=1000 rom=<[email protected]>
postfix/cleanup[21258]: 264F118807D3: message-id=<[email protected]>
postfix/qmgr[21226]: 264F118807D3: \
    from=<[email protected]>, size=366, nrcpt=1 (queue active)
postfix/smtp[21261]: 264F118807D3: to=<[email protected]>, \
    relay=mail.myhosting-provider.com[5.6.7.8]:25, delay=3.3, \
    delays=0.03/0.01/3.3/0.04, dsn=5.7.1, status=bounced (host \
    mail.myhosting-provider.com[5.6.7.8] said: 550 5.7.1 Service unavailable; \ 
    client [1.2.3.4] blocked using zen.spamhaus.org (in reply to RCPT TO command))                               
postfix/cleanup[21258]: 7D65918807E6: message-id=<[email protected]>
postfix/bounce[21264]: 264F118807D3: sender non-delivery notification: 7D65918807E6
postfix/qmgr[21226]: 7D65918807E6: from=<>, size=2393, nrcpt=1 (queue active)
postfix/qmgr[21226]: 264F118807D3: removed
postfix/smtp[21261]: 7D65918807E6: to=<[email protected]>, \
    relay=mail.myhosting-provider.com[5.6.7.8]:25, delay=3.2, \
    delays=0.01/0/3.1/0.03, dsn=5.7.1, status=bounced (host \
    mail.myhosting-provider.com[5.6.7.8] said: 550 5.7.1 Service unavailable; \
    client [1.2.3.4] blocked using zen.spamhaus.org (in reply to RCPT TO command))                   

It seems something about the relaying by postfix is different to the SMTP info that Thunderbird is sending.

I assume the configuration on my mail hosting provider is just set up to block relayed SMTP, and that there’s a fundamental difference betweeen that and what Thunderbird is doing.

If so, can I do this at all? Is there a way to configure postfix to use simple SMTP protocol, assuming it’s not?

My answer:


Your home/home office IP address is blacklisted for sending email at Spamhaus, as most residential IP addresses are. Any mail recipient whose server subscribes to these blackhole lists will reject your attempts to send mail.

Your options are:

  • Move your mail server out of the house.
  • Switch your Internet connection to business class service.

View the full question and any other answers on Server Fault.

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