On 2006-02-28 at 11:51 -0300, Diego Angelini wrote:
> Actually, we have restricted the message size that exim can
> proccess by message_size_limit directive.
This value is advertised to the sender host in SMTP; you can change it
based upon where someone connects _from_ but not by recipient: it's sent
to the sender before the sender tells your system that it has a mail
it'd like you to accept.
You can do things with checking size limits in a RCPT ACL, but at this
point you're going against the spirit of the email standards and against
the established mechanism for handling size limits, so various email
clients may fail ungracefully and you're risking causing more problems
than you solve. Also, an email sender doesn't need to supply the size
ahead of time and the server shouldn't reject the mail if the size is
wrong, so you can only get the reliable real size at the end of DATA
when you've already received the email.
Annotating with 'C' for Client and 'S' for Server, look for the Server
saying "SIZE <value of message_size_limit>" and then later the Client
supplying the "SIZE=<claimed value>" parameter to the MAIL verb:
$ telnet mail.server.example.org 25
Trying 192.0.2.1...
Connected to localhost.
Escape character is '^]'.
S: 220 example.org ESMTP - NO UCE NO UBE 2006-03-01 14:14:35 (UTC)
C: EHLO my.host.name
S: 250-mail.server.example.org Hello my.host.name [192.0.2.50]
S: 250-SIZE 67108864
S: 250-EXPN
S: 250-PIPELINING
S: 250 HELP
C: MAIL FROM:<diego@???> SIZE=1000
S: 250 OK
C: RCPT TO:<postmaster@???>
S: 250 Accepted
C: DATA
S: 354 Enter message, ending with "." on a line by itself
C: [... the email, 200MB large ...]
C: .
S: 250 OK id=1FES9c-0007XL-VD
C: QUIT
S: 221 250-mail.server.example.org closing connection
--
I am keeping international relations on a peaceable footing.
You are biding your time before acting.
He is coddling tyrants.
-- Roger BW on topic of verb conjugation
