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554 SMTP Sync error

Posted on 2011-02-21
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Last Modified: 2013-12-18
Hi there

I am battling to send mail to one specific domain.

if i try to telnet to the MX records ip and do the normal helo, mail from etc, i get the 554 SMPT sync error. (if i run the full command and dont wait for the returns from the recipient server.

if i send just the telnet xxx.xxx.xxx.xxx 25 command, and then wait till i get the response it goes further, but when i send the helo, it gives me:
---------------
220 spool.XXXXXX.com ESMTP Exim 4.69 Mon, 21 Feb 2011 09:57:36 +0200
"helo
501 Syntactically invalid HELO argument(s)"
----------------

any ideas? it seems this is the only domain that is giving me this problem?

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Question by:kingalton
6 Comments
 
LVL 19

Expert Comment

by:bevhost
ID: 34947879
Some servers will get upset if you don't wait for each response before sending the next command
eg: in postfix see http://www.postfix.org/postconf.5.html#reject_unauth_pipelining

The HELO (or EHLO) command must be followed by a FQDN hostname.
eg
HELO myserver.mydomain.com
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Expert Comment

by:bevhost
ID: 34947885
Are you using cpanel?
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Expert Comment

by:PsiCop
ID: 34947909
What exactly do you send at the HELO banner?

You should wait for the system's HELO banner. Why aren't you?

A standard anti-SPAM tactic is to automatically consider any pre-greeting traffic as the hallmark of a spammer. Ordinary senders shouldn't have any problem waiting to see the greeting before sending their own HELO.
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Author Comment

by:kingalton
ID: 34948860
I am just using the telnet commands to test why our trend IMSS server is not getting mails through to he domain, the IMSS server should be sending the correct info out, with the correct SMTP "strings".

but i cannot get mail through to this domain.

the ip i am trying to send to is: 192.96.88.150
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Accepted Solution

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noci earned 500 total points
ID: 34957048
The site in question actualy validates if the site mentioned AFTER the helo is the address it receives mail from....

And it will tarpit your connection if you exceed it's rules.
These are all anti spam methods. And they are easy to implement on exim...

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Expert Comment

by:gheist
ID: 38206084
exim can process smtp commands in all-smalls and otherwise hand-typed.
but once it detects sync error it simply disregards the rest.

if you use some software script that talks SMTP - it is better to use it against your own mail server and let your mail server software talk to the internet.
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