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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for the ‘eMail’ Category

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mail.com (handled by gmx.com) can reject SMTP connections as early as in the EHLO stage

Posted by jpluimers on 2020/04/06

I found this in one of my logs a a while ago:

Error when executing EHLO command for domain mail.com on SMTP server mx00.mail.com.
(554, 'mail.com (mxgmxus007) Nemesis ESMTP Service not available\nNo SMTP service\nBad DNS PTR resource record.\nFor explanation visit http://postmaster.gmx.com/en/error-messages?ip=37.153.243.242&c=rdns')

It means that gmx.de / mail.com are among the strictest email handling providers I know. I don’t blame them: EHLO is at the start of an extended SMTP session.

At [WayBack] Error messages | GMX Postmaster it indicates:

5xy Bad DNS PTR resource record

Emails from your email server were rejected because the PTR Resource Record (PTR-RR) of your IP address does not follow our guidelines. Possible reasons for this can be:

  • The PTR-RR states that the IP address was dynamically allocated.
  • The PTR-RR is a generic standard entry of your provider. Please allocate an independent and fully qualified domain name (Fully Qualified Domain Name – FQDN) to your email server and enter the corresponding valid PTR-RR.
  • Individual rejection of the PTR-RR for system protection reasons. Please contact the administrator of your system who should then contact us.

–jeroen

Posted in Communications Development, Development, eMail, Internet protocol suite, Power User, SMTP, SocialMedia, TCP | Leave a Comment »

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