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My clients server access keeps getting blocked by CSF.
The Exim log produces:

no host name found for IP address X.X.X.X
Exim error SMTP call from [X.X.X.X]:50135 dropped: too many syntax or protocol error.

Am I correct in assuming that this can only be solved by the ISP or connectivity provider?

HBruijn
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Lance Davey
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1 Answers1

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The lack of reverse DNS record is something that should be addressed/facilitated by the owner of the ip-address, typically indeed the ISP or connectivity provider.

The is not the cause of the second error:

too many syntax or protocol error

That is caused a crappy SMTP client that doesn't adhere to the standards (which is typically a good indication of a Spambot).

You can tune that behaviour with the smtp_max_synprot_errors setting.

HBruijn
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  • Thanks HBruijn. The client's email software sends mail using single quotation marks ie 'someone@somewhere.com' she has been using this for a while why is the server only blocking her now? – Lance Davey Oct 27 '15 at 10:38
  • I can't determine that either from the information your provide... – HBruijn Oct 27 '15 at 13:03