На CentOS 7 крутится Exim. Почта ходит нормально, в том числе и с/на mail.ru. В логе вижу массу соединений от серверов mail.ru длительностью 0 секунд:
лог/журнал соединений2017-09-29 16:09:01 SMTP connection from [217.69.141.15] (TCP/IP connection count = 2)
2017-09-29 16:09:01 SMTP connection from [185.5.136.177] (TCP/IP connection count = 3)
2017-09-29 16:09:01 SMTP connection from f373.i.mail.ru [217.69.141.15] closed by QUIT
2017-09-29 16:09:01 SMTP connection from f499.i.mail.ru [185.5.136.177] closed by QUIT
2017-09-29 16:09:01 SMTP connection from [217.69.140.243] (TCP/IP connection count = 2)
2017-09-29 16:09:01 SMTP connection from f347.i.mail.ru [217.69.140.243] closed by QUIT
2017-09-29 16:09:02 SMTP connection from [94.100.185.45] (TCP/IP connection count = 2)
2017-09-29 16:09:02 SMTP connection from f193.i.mail.ru [94.100.185.45] closed by QUIT
2017-09-29 16:09:03 SMTP connection from [217.69.138.162] (TCP/IP connection count = 2)
2017-09-29 16:09:03 SMTP connection from f495.i.mail.ru [217.69.138.162] closed by QUIT
2017-09-29 16:09:03 SMTP connection from [185.5.136.88] (TCP/IP connection count = 2)
2017-09-29 16:09:03 SMTP connection from f417.i.mail.ru [185.5.136.88] closed by QUIT
2017-09-29 16:09:12 SMTP connection from [217.69.141.7] (TCP/IP connection count = 2)
2017-09-29 16:09:12 SMTP connection from f365.i.mail.ru [217.69.141.7] closed by QUIT
2017-09-29 16:09:15 SMTP connection from [217.69.141.11] (TCP/IP connection count = 2)
2017-09-29 16:09:15 SMTP connection from f369.i.mail.ru [217.69.141.11] closed by QUIT
2017-09-29 16:09:16 SMTP connection from [185.5.136.74] (TCP/IP connection count = 2)
2017-09-29 16:09:16 SMTP connection from f403.i.mail.ru [185.5.136.74] closed by QUIT
Диалог выглядит так:
220 MailServer ESMTP
->EHLO f368.i.mail.ru
250-mail.mydomain.ru Hello f368.i.mail.ru [217.69.141.10]
250-SIZE 73400320
250-8BITMIME
250-PIPELINING
250-AUTH CRAM-MD5 LOGIN
250 HELP
->QUIT
Что ему не нравится?
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