550 5.4.318 Message expired, connection reset (SuspiciousRemoteServerError)

albatroz

• April 10, 2020 05:44

Recently, several emails coming from Office365 has started to bounce with the following error message 4/9/2020 6:15:52 PM - Server at SC1P215MB1135.LAMP215.PROD.OUTLOOK.COM returned '550 5.4.318 Message expired, connection reset (SuspiciousRemoteServerError)(450 4.4.318 Connection was closed abruptly (SuspiciousRemoteServerError))' 4/9/2020 5:55:08 PM - Server at YY.YY.YY.YY (XX.XX.XX.XX) returned '450 4.4.318 Connection was closed abruptly (SuspiciousRemoteServerError)'

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  albatroz

  • April 10, 2020 11:15

  I added the following IPs to the "Trusted SMTP IP addresses" Access List in the Exim Configuration Manager but I don't know if it would be enough 20.180.141.23 20.180.141.18

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  albatroz

  • April 10, 2020 15:57

  Something I discovered is that some of the IPs that were bounced were out of the IPs declared in this document published by Microsoft

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  cPanelLauren

  • April 10, 2020 22:09

  Is the following enabled in the exim configuration? Ratelimit suspicious SMTP servers If so it sound like the servers aren't terminating the connection properly based on the error and the description for the setting: [QUOTE]

  Ratelimit incoming SMTP connections that do not send QUIT (violates RFCs), have recently matched an RBL, or have attacked the server.

  
  But Microsoft also has some information on this in their own forums and I'd suggest reading it over prior to making any changes: '550 5.4.300 Message expired'

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  reddot

  • April 23, 2020 10:28

  I have the same problem too. I get complains from my customer once in a month or two. And always from Office 365 senders. 4/22/2020 10:21:34 AM - Server at VE1P191MB0910.EURP191.PROD.OUTLOOK.COM returned '550 5.4.318 Message expired, connection reset (SuspiciousRemoteServerError)(450 4.4.318 Connection was closed abruptly (SuspiciousRemoteServerError))' 4/22/2020 10:00:50 AM - Server at mail.xxx.com (xxx.xxx.xxx.xxx) returned '450 4.4.318 Connection was closed abruptly (SuspiciousRemoteServerError)' I could not find anything in my log. I have no idea why this is happening. Anyone can help?

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  cPanelLauren

  • April 23, 2020 16:58

  What do you mean you couldn't find anything in your log. The output there is log output. The issue appears to be the same as what I described in my last response.

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  RSL

  • April 21, 2021 15:08

  I have the same problem too from Office 365 senders when are multiple recipients. Server at DBBP189MB1193.EURP189.PROD.OUTLOOK.COM returned '550 5.4.318 Message expired, connection reset (SuspiciousRemoteServerError)(450 4.4.318 Connection was closed abruptly (SuspiciousRemoteServerError))' Server at mail.xxxxxxxx.com (xx.xx.xx.xx) returned '450 4.4.318 Connection was closed abruptly (SuspiciousRemoteServerError)' With a one recipient, the e-mails are received. Disable Ratelimit suspicious SMTP servers does not solve this problem. Any idea?

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  cPRex Jurassic Moderator

  • April 21, 2021 16:50

  Could you try disabling the "Introduce a delay into the SMTP transaction for unknown hosts and messages detected as spam" setting in WHM >> Exim Configuration Manager? I've seen that cause similar issues in the past. You could also try adding the IPs listed at Office 365 URLs and IP address ranges - Microsoft 365 Enterprise to /etc/trustedmailhosts to see if that takes care of things and lets the mail get through properly.

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  RSL

  • April 22, 2021 15:10

  Hi, disabling the "Introduce a delay into the SMTP transaction for unknown hosts and messages detected as spam" setting in WHM >> Exim Configuration Manager, has worked for me. Thank's cPRex

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  cPRex Jurassic Moderator

  • April 22, 2021 15:11

  I'm glad that's all it took :D

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