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I currently have several servers at OVH including one that acts as a personal mail server. Postfix takes care of receiving the mails, but I have a problem for the reception coming from certain domains. After investigation I noticed that often the domains in question were hosted on the amazon network.

  • Impossible to receive mails from amazon, adobe (54.240.14.29, 54.240.14.30 => amazon), pinterest (some mails also amazon).
  • No problem to receive emails from gmail, outlook, mail.com, protonmail, between my personal domains.
  • No iptables rules specific to ip.
  • Postfix does not react at all to these connections with a smtpd -v in master.cf.
  • tcpdump port 25 -s 0 -i any gives me as output:
00: 02: 41.274707 IP a27-171.smtp-out.us-west-2.amazonses.com.43934> srv.xxxxx.xxx.smtp: Flags [S], seq 1358324291, win 26883, options [mss 8961, sackOK, TS 55510897 ecr 0, nop, wscale 7], length 0
00: 02: 43.290697 IP a27-171.smtp-out.us-west-2.amazonses.com.43934> srv.xxxxx.xxx.smtp: Flags [S], seq 1358324291, win 26883, options [mss 8961, sackOK, TS 55512913 ecr 0, nop, wscale 7], length 0
00: 02: 47.450683 IP a27-171.smtp-out.us-west-2.amazonses.com.43934> srv.xxxxx.xxx.smtp: Flags [S], seq 1358324291, win 26883, options [mss 8961, sackOK, TS 55517073 ecr 0, nop, wscale 7], length 0

and then nothing.

Does anyone have such a concern and if so how did it settle?

Thanking you for your attention!

  • Check your firewall again. – Michael Hampton May 28 at 23:28
  • thx but the result is same with disabled firewall iptables --flush – MarcEteint May 29 at 0:03
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Thank you, the problem is solved

I had a static route 54.0.0.0/8 route that prevented me from responding to the Amazon server.

Have a nice day at the forum.

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