Outlook ignores Message limit set by SMTP server

[George_GR]

I use an SMTP server (Mailenable) for my outgoing mail that has set a message
size limit of 10 MB. When I try to send an email larger than the limit
Mailenable rejects it but Outlook instead of informing me about the fact and
stopping the effort, it keeps trying to send the message constantly, keeping
up an outgoing traffic that consumes all my uploading bandwidth.
When I send the same message through Thunderbird, upon connection to the
SMTP server it tells me "Message exceeds the size limit enforced by the SMTP
server" and stops the useless effort without trying to send even one byte
more.
This certainly is A BUG (Outlook ignores the response sent by the SMTP
server) which MS HAS to take care of...

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[George_GR]

Talking about Office system 2007 (I did not check what outlook express does).

 

[N. Miller]

I use an SMTP server (Mailenable) for my outgoing mail that has set a message
size limit of 10 MB. When I try to send an email larger than the limit
Mailenable rejects it but Outlook instead of informing me about the fact and
stopping the effort, it keeps trying to send the message constantly, keeping
up an outgoing traffic that consumes all my uploading bandwidth.

How does "Mailenable" perform the reject? Should be a standard "55x" error
code during the SMTP transaction. MS Outlook has been around a few years,
and seems to handle SMTP "55x" error responses properly.

 

[George_GR]

I cannot come into that much of detail about Mailenable, but I can say that
it's a very popular email server software and runs to many many servers as it
is distributed along (as the default mail server) with the (very popular as
well) PLESK control panel for web servers (runs on thousands of web servers).
I think they give some info about
their response codes here
http://www.mailenable.com/kb/Content/Article.asp?ID=me020032

Mailenable: http://www.mailenable.com
Plesk : http://www.parallels.com/en/products/plesk/

I repeat that this whole thing is not an issue for Thunderbird which handles
the situation perfectly. (I do not say this in advandage of Thunderbird, but
just to make the point that Mailenable does send back the appropriate
response)

This is something that has to be solved anyway because Plesk (which means
Mailenable SMTP) is widely used by Web servers and Outlook is widely used as
mail client. This is an "explosive" bandwith-eating combination in cases that
(non-power-user) people tries to send a message that's larger than the size
limit Mailenable SMTP connector is setup to accept...

 

[Brian Tillman [MVP - Outlook]]

I cannot come into that much of detail about Mailenable,

You should be able to examine the rejection message and look at the code
MailEnable gave you.

 

[George_GR]

You mean it should be mentioned in the "rejection" message that thunderbird
gives?

 

[Brian Tillman [MVP - Outlook]]

You mean it should be mentioned in the "rejection" message that
thunderbird
gives?

Usually, yes.

 

[N. Miller]

"N. Miller" wrote:

I cannot come into that much of detail about Mailenable, but I can say that
it's a very popular email server software and runs to many many servers as it
is distributed along (as the default mail server) with the (very popular as
well) PLESK control panel for web servers (runs on thousands of web servers).
I think they give some info about
their response codes here
http://www.mailenable.com/kb/Content/Article.asp?ID=me020032

Mailenable: http://www.mailenable.com
Plesk : http://www.parallels.com/en/products/plesk/

I repeat that this whole thing is not an issue for Thunderbird which handles
the situation perfectly. (I do not say this in advandage of Thunderbird, but
just to make the point that Mailenable does send back the appropriate
response)

This is something that has to be solved anyway because Plesk (which means
Mailenable SMTP) is widely used by Web servers and Outlook is widely used as
mail client. This is an "explosive" bandwith-eating combination in cases that
(non-power-user) people tries to send a message that's larger than the size
limit Mailenable SMTP connector is setup to accept...

I would suggest turning on logging in Outlook, then. SMTP transaction is
pretty straightforward:

| Client> "EHLO machine.name"
| Server> "Pleased to meet you, machine.name."
| Client> "MAIL FROM: <[email protected]>"
| Server> "<[email protected]> OK, send RCPTs."
| Client> "RCPT TO: <[email protected]>."

And so on. Unless there is some kind of ACL check by "Server" before
"Client" sends "EHLO...", in which case, "Server" may send a 5xx error. But,
that may be "out of order". I use Mercury/32 as my MTA, and here is a
snippet of the server log for a reject:

| T 20080923 001107 48d120de Connection from 69.42.171.206
| T 20080923 001107 48d120de HELO host206.firstchoicecolos.com
| T 20080923 001108 48d120de MAIL FROM:<[email protected]>
| E 20080923 001108 48d120de Host 69.42.171.206 blocked by Spamhaus - message rejected.
| T 20080923 001108 48d120de QUIT
| T 20080923 001108 48d120de Connection closed with 69.42.171.206, 1 sec. elapsed.

So the sending host got as far as the "MAIL FROM:" command before my server
refused the connection. If "MailEnable" is sending responses out of the
expected order, MS Outlook may be thrown for a loop. Maybe the client should
be able to handle broken servers, if, in fact, the server is broken? Hard to
say what is bollixed up, but activating the Outlook logging feature might
help to figure it out; or checking the "MailEnable" logs.

 

[Kerem ERSOY]

Hi,

I had a similar situation. I am using PostFix as an SMTP server and my out
look 2007 delivers to it.

I have a size limit of 20 MB's set on the Postfix.

Now whem I add a say 40 MB attachment to an e-mail ans sent it to the server
outlook ignores the ehlo size attribute as thepostfix server sends to it.

In fact this is how SMTP normally works. When a MTA (Mail Transfer Agent)
opens a connection to the MUA (Mail User Agent), MUA says
EHLO <hostname>
and the MTA responds with a limtations string. When I enable tracing in my
outlook this is what happens during the initial contact.

2008.11.15 16:14:31 SMTP (a.x.com): [tx] EHLO ddd
2008.11.15 16:14:31 Kerem ERSOY - Corporate: UploadItems: 0 messages to send
2008.11.15 16:14:31 SMTP (a.x.com): <rx> 250-a.x.com
2008.11.15 16:14:31 SMTP (a.x.com): <rx> 250-PIPELINING
2008.11.15 16:14:31 SMTP (a.x.com): <rx> 250-SIZE 20971520
2008.11.15 16:14:31 SMTP (a.x.com): <rx> 250-VRFY
2008.11.15 16:14:31 SMTP (a.x.com): <rx> 250-ETRN
2008.11.15 16:14:31 SMTP (a.x.com): <rx> 250-AUTH CRAM-MD5 PLAIN DIGEST-MD5
LOGIN
2008.11.15 16:14:31 SMTP (a.x.com): <rx> 250-AUTH=CRAM-MD5 PLAIN DIGEST-MD5
LOGIN
2008.11.15 16:14:31 SMTP (a.x.com): <rx> 250 8BITMIME


As you would notice the postfix returns a SIZE attribute. What should happen
then is the MTA check the content size and if the content size is larger than
the SIZE attribute. IT should immediately stop the delivery and return user
with an error message.

This is what happens when 2 MTAS's want to tranfer a message between each
other.

But Outlook ignores the SIZE and starts to send the message. The MTA listens
to the message and sends an error message only after the whole message is
transferred to itself.

So it seems that Outlook does not check the SIZE attribute that the server
returns. This is a bug and should be fixed.

Cheer,
Kerem ERSOY

 

[Kerem ERSOY]

The "55x" comes only all the mail was transferred to the MTA.

Cheers,
K.

 

[Kerem ERSOY]

In your example host responds with helo:

T 20080923 001107 48d120de HELO host206.firstchoicecolos.com
| T 20080923 001108 48d120de MAIL FROM:<[email protected]>

This should not happen. Helo is only for ackwards compatiblity. Microsoft
says they are currently using this RFC's for implementation:


http://support.microsoft.com/kb/155455/en-us

(as of January, 14 2007).

The problem here is Microsoft says it is using :

The RFCs used in the research for this article are:
RFC821 - Simple Mail Transfer Protocol (SMTP)
RFC1869 - SMTP Service Extensions (ESMTP)

This is an old document, which is lacking "size" parameter and been
superseded long ago by :

RFC2821 - Simple Mail Transfer Protocol

It clearly says that it obsoletes these RFCS:

Network Working Group J. Klensin, Editor
Request for Comments: 2821 AT&T Laboratories
Obsoletes: 821, 974, 1869 April 2001
Updates: 1123
Category: Standards Track


Simple Mail Transfer Protocol

This RFC talks about the SIZE parameter which Microsoft Developers are
ignoring since 2001 !!!

So we should expect the "outdated" developers have find time (before a new
RFC comes or they are Retired with big $$$ whicever happens first) to
"discover" and follow never RFC's to internet standards and implement it
properly.

Cheers,
K.