SMTP connections are being made to the Symantec Mail Gateway (SMG) that do not begin with the HELO or EHLO SMTP command.
Early RFCs defining the SMTP protocol did not require or even define the HELO command (notably RFC788). However, starting with RFC821 and currently in RFC2821, one of EHLO or HELO is required. As such, much older SMTP clients may not implement a version of SMTP newer than RFC788.
Currently the Symantec Mail Gateway cannot be configured to reject or defer SMTP connections that do not begin with the HELO or EHLO commands.
This has been raised as a potential enhancement for a future product release and this knowledge base article will be updated when the feature is made available.
Imported Document ID: TECH162395
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