Sender verify failed

RK-BZ

• September 06, 2020 10:25

We have a problem with receiving e-mails via Microsoft 365. Our server partially rejects incoming e-mails since September 1st 2020. We have now received a recommendation that maybe an update to Exim version 4.94 will help. Could an update be the solution to the problem or is there another cause? cPanel 90.0.5 Exim: exim-4.93-5.cp1186.x86_64

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  nixuser

  • September 07, 2020 17:36

  possible to post the log entries here?

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  RK-BZ

  • September 07, 2020 21:40

  H=mail-xxx.outbound.protection.outlook.com (EUR05-xxx.outbound.protection.outlook.com) [xxx]:57088 sender verify fail for : mx08.domain.com [xxx.xxx.xx.xx] : SMTP error from remote mail server after RCPT TO:: 550 5.7.1 Bounce attack signature verification failed. H=mail-xxx.outbound.protection.outlook.com (EUR05-xxx.outbound.protection.outlook.com) [xxx]:57088 X=TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no F= rejected RCPT : Sender verify failed H=mail-xxx.outbound.protection.outlook.com (EUR05-xxx.outbound.protection.outlook.com) [xxx]:57088 Warning: "Detected session with all messages failed" H=mail-xxx.outbound.protection.outlook.com (EUR05-xxx.outbound.protection.outlook.com) [xxx]:57088 Warning: "Increment slow_fail_block Ratelimit - mail-xxx.outbound.protection.outlook.com (EUR05-xxx.outbound.protection.outlook.com) [xxx]:57088 because of all messages failed"
  

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  keat63

  • September 08, 2020 07:57

  Personally, I'd suggest that the update of exim is a techs way of saying that they don't know what the problem is, so lets update first and rule that out. However as @nixuser suggests, getting hold of the reject notification, message headers and log entries would be a good start. Also, if not already, consider adding SPF and DKIM entries to your DNS.

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  cPanelLauren

  • September 08, 2020 16:38

  The threads here may be helpful:

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