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emailexim

How do I fix "501 Syntactically invalid HELO argument(s)"?

I'm using exim on both the sending and relay hosts, the sending host seems to offer:

HELO foo_bar.example.com

Response: 

501 Syntactically invalid HELO argument(s)
Solution

  • Possibly a problem with underscores in the hostname? http://www.exim.org/lurker/message/20041124.113314.c44c83b2.en.html