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Weird SMTP problem - 15.Feb.2002 2:28:00 PM

dj@paregos.se

Posts: 1
Joined: 15.Feb.2002
Status: offline

I have a really weird problem with sending SMTP-mail. I cant send mail to some hosts. When I use telnet and connect to the host on port 25 i get the following error:

421 mail.domain.com is not accepting new connections. Please try later

But only for some hosts. When i try to connect to the same host, using an other firewall, it works fine. Does anyone have any ideas??

Post #: 1

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RE: Weird SMTP problem - 15.Feb.2002 4:52:00 PM

AlexS

Posts: 150
Joined: 4.Feb.2002
Status: offline

First of all, SMTP server cannot detect what system type is attempting to connect (until it receives SMTP headers with routing information).

I am almost sure this issue is not connected to ISA. The only thing that "differentiates" your ISA server from others (during initial connection) is IP Address/FQDN. If receiving server is somehow configured to reject connections from your ISA, the response would be dirrerent.

In your case, the code 421 looks like Enhanced Mail System Status Code (RFC-1893).

In accordance with that RFC-1893:
....
4.X.X Persistent Transient Failure

A persistent transient failure is one in which the message as
sent is valid, but some temporary event prevents the successful
sending of the message. Sending in the future may be successful.
....
X.2.1 Mailbox disabled, not accepting messages

The mailbox exists, but is not accepting messages. This may
be a permanent error if the mailbox will never be re-enabled
or a transient error if the mailbox is only temporarily
disabled.
....
------------
Combining 4.X.X and X.2.1 (=4.2.1), looks that Server "mailbox" (message delivery component) is out of "sockets" (you know, most SMTP servers can be configured with "maximum connections" value).

Happy ISAing...

Alex

[ February 15, 2002, 04:55 PM: Message edited by: AlexS ]

(in reply to dj@paregos.se)

Post #: 2