pls help on: 523 Message length (10485822 bytes) exceeds administrative limit (10485760)

Hi

I am unable to download a message with several large attachments.

Log says:

523 Message length (10485822 bytes) exceeds administrative
limit(10485760).
sendmail: Unable to submit message.
fetchmail: reading message <mymail>@pop3.<myDomain>:13 of 18 (12384194
octets) (log message incomplete)
fetchmail: MDA returned nonzero status 67
fetchmail:  not flushed

I have already asked help on this a couple of years ago, but I do not
remember if/how  we fixed it (I doubt we did).

It seems to be a issue with sendmail (or maybe, with the courier
limited version of sendmail), but I do not how to check/reset sendmail
configuration. 

Your advise is welcome
Thanks Cheers
mario