Hello all, please help identify the root cause of the issue I'm facing. Since a while back all emails attemted to be sent to any company laveraging Office 365 (connection goes via ***.protection.outlook.com) are failing with no reason provided
Exampl:microsoft.com
Getting responsible mx server
Nslookup mx
> microsoft.com
microsoft.com MX preference = 10, mail exchanger = microsoft-com.mail.protection.outlook.com
microsoft-com.mail.protection.outlook.com internet address = 104.47.53.36
now trying to connect via console
telnet microsoft-com.mail.protection.outlook.com 25
220 BL2NAM06FT003.mail.protection.outlook.com Microsoft ESMTP MAIL Service ready at Thu, 31 Oct 2019 15:47:32 +0000
HELO mx.mydomainhere.ru
(hangs for ~30 sec)
connection closed
That's it! No information at all while trying to send an email.
Here is an example of sending to gmail.com as another example where there are no issues, same as all others not using O365.
nslookup mx
gmail.com MX preference = 40, mail exchanger =
alt4.gmail-smtp-in.l.google.com
alt4.gmail-smtp-in.l.google.com internet address = 209.85.146.27
telnet alt4.gmail-smtp-in.l.google.com 25
220 mx.google.com ESMTP *** - gsmtp
HELO mx.mydomainhere.ru,
250 mx.google.com at your service,
226086,sending message
MAIL FROM:<***@mydomainhere.ru>,
250 2.1.0 OK *** - gsmtp,
RCPT TO:<***@gmail.com>,
250 2.1.5 OK *** - gsmtp,
DATA,
354 Go ahead g28si3712191ljn.11 - gsmtp,
250 2.0.0 OK 1572481571 *** - gsmtp,
QUIT,
221 2.0.0 closing connection ** - gsmtp,
Local
Any ideas on how to troubleshoot this? Many thanks