Subject: [imapext] Problem with Yahoo SMTP server SIZE attribute.

From: narendra singh bisht <[email-masked]>
Date: Thu, 2 Apr 2015 11:19:24 -0400

Hi all,

I am facing a problem with Yahoo account.

Yahoo SMTP server broadcast the SIZE as "SIZE 41697280".

So when I am trying to send a mail with ~28.8 MB of attachment to Gmail/AOL,
sending of the mail succeeds but I am getting a MAILER-DAEMON saying :

*Remote host said:*
*552-5.2.3 Your message exceeded Google's message size limits.*

What should I do, as a mail client. Should i not honor the SIZE attribute
and use 25 MB as the upper limit?

-- 
Thanks & Regards
-Naren

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From: Ned Freed <[email-masked]>
Date: Thu, 02 Apr 2015 16:00:47 -0700 (PDT)

> Yahoo SMTP server broadcast the SIZE as "SIZE 41697280".

Which means that Yahoo won't accept any message larger than that. It does
not mean that they will accept any message that's smaller. There can be
per-account limits, per-domain limits, limits due to forwarding somewhere
else, etc. etc. etc.

> *552-5.2.3 Your message exceeded Google's message size limits.*

Huh? What does sending to Google have to do with sending to Yahoo?

> and use 25 MB as the upper limit?

The SIZE EHLO response is an optimization: It tells you in advance that if you
have a message larger than the limit, you might as well not bother trying to
send it. It does not tell you what the actual limit is on your transaction. And
it most certainly does not tell you squat about what the limit is going to be
somewhere else.

You seem to be looking for some secret sauce here that does not and cannot
exist: A limit that will magically prevent problems trying to send large
messages.

Your responsibility as a mail client developer is first to look at the SIZE
EHLO response and not bother trying to send the message. Additionally, if the
server supports the extension you should pass the message size as a SIZE
parameter on MAIL FROM so that the server can apply destination-specific  size
limits and return appropriate responses.

If, in addition to doing this, you also want to impose a local limit, by all
means do that, but unless it's absurdly low it's not going to prevent messages
being bounced due to size limitations.

				Ned

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From: Gulbrandsen <[email-masked]>
Date: Fri, 3 Apr 2015 07:42:58 +0000

There are two size limits here: the size limit at the submission server 
(yahoo) and that at the final destination (gmail). The second is 
smaller than the first, which leads to a DSN.

There is nothing to do 
about that. It is regrettable, but no action by an SMTP client or 
server in one hop will affect that later hop.

Arnt