Re: [Nmh-workers] reason: 554 5.7.0 Message Size Violation

[Ken Hornstein]

>This is the first I've ever heard of this rejection reason. The message
>consisted, almost entirely, of an attachment, Spec_05_04_10:04.zip, a
>471,282 byte zip file.

That seems kinda small to me ... but see below.

>Is there anything I can do, short of breaking the attachment into
>several pieces, and sending separately?

AFAIK, no (I will note that there is stuff in nmh to do MIME-splitting properly,
but I don't know if the remote side will handle it properly; it's one of
those lesser-implemented corners of the MIME spec).

>Is there some way, other than trial and error, to determine the size
>limit?

Well, in theory you'd connect to the server MX and ask for it.  So ...

% host -t mx mac.com
mac.com mail is handled by 10 mx5.mac.com.akadns.net.
mac.com mail is handled by 10 mx6.mac.com.akadns.net.
mac.com mail is handled by 10 mx1.mac.com.akadns.net.
mac.com mail is handled by 10 mx2.mac.com.akadns.net.
mac.com mail is handled by 10 mx3.mac.com.akadns.net.
mac.com mail is handled by 10 mx4.mac.com.akadns.net.

But if you do that:

% telnet mx1.mac.com.akadns.net 25
Connected to mx1.mac.com.akadns.net (17.172.34.9).
Escape character is '^]'.
220 st11p00mm-smtpin005.mac.com -- Server ESMTP (Oracle Communications 
Messaging Server 7u4-26.01(7.0.4.26.0) 64bit (built Jul 13 2012))
EHLO foo.com
250-st11p00mm-smtpin005.mac.com
250-8BITMIME
250-PIPELINING
250-CHUNKING
250-DSN
250-ENHANCEDSTATUSCODES
250-EXPN
250-HELP
250-XADR
250-XSTA
250-XCIR
250-XGEN
250-XLOOP A01954DA91912D5E76B2E4FE47298004
250-ETRN
250-NO-SOLICITING
250 SIZE 0

The last one is key.  "SIZE" is supposed to tell you the maximum message
size the server will accept.  It's defined in RFC 1870:

        http://tools.ietf.org/html/rfc1870

But their SIZE parameter is 0.  That means (according to section 3 of
RFC 1870) "that no fixed maximum message size is in force".  So ... you
don't really know.

I remember we had to bump our maximum message size at work up from
10 megabytes because people kept sending stuff that was larger than
that ... and that was a decade ago.  If I had to guess I'd say that
the limit here was around a half a megabyte (remember that your zip
file will be inflated by around 30% when it's base64 encoded into
your email).

--Ken