always_bcc and aliases file size problems

I wanted to save a copy of all mails passing through the company mail server
(yes, everybody knows I'm logging, and it's for legitimate reasons).

So, I put inside postfix's main.cf :
always_bcc = allmailbackup

Then, in my aliases file, I put a line :
allmailbackup: /var/spool/mail/backup/allmail

And, I configured logrotate to rotate that file every day.

That got me a copy of every mail received or sent by anyone in the company,
logged to that file, so I could examine it with mutt or elm, or extract
messages with grepmail etc..

No problem so far. It's been running fine for a week now, until tonight.

I just found that file has grown to 50MB, when it's usually only half that or
less, which is possible due to normal circumstances, but suspicious.

The big problem was that there was mail stuck in the mailq which was refusing
to save mail to that file because the file was too big.

Is there a 50MB limit on the size of files which will be delivered to using
the aliases method ?

I know an alternate method would be to have a real user set up as
allmailbackup, but I've got a system wide spamassassin set up which I don't
want to trigger on those mails. There's probably a way around that, but I want
to understand what's wrong with my existing method first.

Thanks,

Chris

Skip to the end to see where I answer my own question ...............


On Wed, 16 Jun 2004 23:48:44 +0800, Chris Severn <severn@iinet.net.au> wrote:

>I wanted to save a copy of all mails passing through the company mail server
>(yes, everybody knows I'm logging, and it's for legitimate reasons).
>
>So, I put inside postfix's main.cf :
>always_bcc = allmailbackup
>
>Then, in my aliases file, I put a line :
>allmailbackup: /var/spool/mail/backup/allmail
>
>And, I configured logrotate to rotate that file every day.
>
>That got me a copy of every mail received or sent by anyone in the company,
>logged to that file, so I could examine it with mutt or elm, or extract
>messages with grepmail etc..
>
>No problem so far. It's been running fine for a week now, until tonight.
>
>I just found that file has grown to 50MB, when it's usually only half that or
>less, which is possible due to normal circumstances, but suspicious.
>
>The big problem was that there was mail stuck in the mailq which was refusing
>to save mail to that file because the file was too big.
>
>Is there a 50MB limit on the size of files which will be delivered to using
>the aliases method ?
>
>I know an alternate method would be to have a real user set up as
>allmailbackup, but I've got a system wide spamassassin set up which I don't
>want to trigger on those mails. There's probably a way around that, but I want
>to understand what's wrong with my existing method first.
>
>Thanks,
>
>Chris

OK, I managed to find the answer, and it's this line in
/usr/doc/postfix-2.0.19/defaults :
mailbox_size_limit = 51200000

According to "man 8 local",
mailbox_size_limit
Limit the size of a mailbox etc. file (any file that is written
to upon delivery). Set to zero to disable the limit.

So, that's answers my question.

Oh, and I found why my file had doubled in size - because someone decided to
send an email with a 5MB attachment to 5 separate people inside the company.
Now I'm off to search for the option for limiting attachment sizes........

Thanks,

Chris