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I'm sending out automated emails to some users and I get this error message back on undeliverable emails. The strange thing is that it's for only one domain (*

What multiple parameters does it mean?

(Strangely, I'm also getting bounced by another domain * for multiple users stating "User is unknown {mx063}".)

Is this related to DNS PTR records? The email server I am using has only recently been set up.

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migrated from Jul 14 '10 at 1:01

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What implementation of SMTP are you using? – You Jul 10 '10 at 19:55
Hi, I'm using SmarterMail 6.9 – alj Jul 11 '10 at 21:51
up vote 1 down vote accepted

The RFCs governing the SMTP protocol state that the HELO statement should have only one value.

250 Welcome,, glad to meet you

If the HELO statement has a space in it for some reason, some mailers will see that as something extra and puke on it. Others will just ignore it.

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Cheers for that sysadmin1138. – alj Jul 15 '10 at 7:55
The MAIL FROM command in your example is not syntactically valid. (Though many mail servers are forgiving enough about syntax errors to accept it anyway.) – kasperd Feb 29 at 9:37

.... just incase anyone else has the same problem, you have to go into Admin and set the HELO property to your domain.

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This answer is of no use unless you tell us what email server you're using – Mark Henderson Jul 14 '10 at 1:24
... SmartMail 6.9 ... as in the comments above. – alj Jul 15 '10 at 7:54

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