-1

I've only recently been made aware that Azure has now blocked VM's from sending email directly to other email servers (which has been working fine up until the last month), and am currently attempting to switch over to a relay through Office 365 as a smart host.

Part of this was to change SMTP servers to Postfix from SendMail which has gone smoothly. However, I've now got my mail.log file filling with the below:

Aug 15 14:16:06 tb-ha1 postfix/smtpd[3931]: lost connection after CONNECT from unknown[168.63.129.16]
Aug 15 14:16:06 tb-ha1 postfix/smtpd[3931]: disconnect from unknown[168.63.129.16]
Aug 15 14:16:06 tb-ha1 postfix/smtpd[3931]: connect from unknown[168.63.129.16]
Aug 15 14:16:06 tb-ha1 postfix/smtpd[3924]: lost connection after CONNECT from unknown[13.78.64.11]
Aug 15 14:16:06 tb-ha1 postfix/smtpd[3924]: disconnect from unknown[13.78.64.11]
Aug 15 14:16:21 tb-ha1 postfix/smtpd[3931]: lost connection after CONNECT from unknown[168.63.129.16]
Aug 15 14:16:21 tb-ha1 postfix/smtpd[3931]: disconnect from unknown[168.63.129.16]
Aug 15 14:16:21 tb-ha1 postfix/smtpd[3924]: connect from unknown[168.63.129.16]
Aug 15 14:16:32 tb-ha1 postfix/smtpd[3931]: connect from unknown[13.78.64.11]

I've checked the IP addresses and they appear to be owned by Azure...and one of them is the Azure DNS server?

Can anyone shed any light on the resolution for this please?

Thanks,

Craig.

Craig McCormack
  • 21

1 Answers1

0

i don't know about Azure, but i think it's a Dos attack use Fail2ban and secure your postfix

i think it will help you check mail section

Shanu T Thankachan
  • 993
  • 2
  • 8
  • 16