On 2008-11-12 16:55, John Lange wrote:
Just in case someone stumbles on this thread; I never did do anything to solve this problem but it just seemed to go away on it's own.
I suspect this is a form of Google greylisting. Once google gets to know you a bit better it stops delaying your mail.
...
451 4.5.0 SMTP protocol violation see RFC 2821
Usually, an error message like that would suggest something is messed up in the MTA configuration at one end or the other. Did you bother to check this site for likely possibilities?...
http://www.rfc-ignorant.org/rfcs/rfc2821.php