SmartEvent NGSE fails to send auto-reaction e-mails.

Debug of CPSEMD daemon on SmartEvent NGSE (per sk105806) shows:

SMTP server error code - 501
SMTP server error message - Syntax: HELO hostname

CInternalMailCommand::Execute: SendMail failed
.--> 0x... CBasicAutoReaction::_OnFinishExecution
..--> 0x... CAutoReact::OnAutoReactionFinishExecution
..<-- 0x... CAutoReact::OnAutoReactionFinishExecution
.<-- 0x... CBasicAutoReaction::_OnFinishExecution
<-- 0x... CInternalMailCommand::Execute
--> 0x... CAutoReact::_DoOnAutoReactionFinishExecution
CAutoReact::_DoOnAutoReactionFinishExecution: Status: fail (2)
<-- v CAutoReact::_DoOnAutoReactionFinishExecution
                
            
Traffic capture on SmartEvent NGSE shows:
Response: 501 Syntax: HELO hostname\r\n
      Response code: Syntax error in parameters or arguments (501)
      Response parameter: Syntax: HELO hostname