I see there is a potential fix for the mail size logging.
1) when awk is not available, the old (potentially flawed) code is used.
2) additionally, when there is more logging to the mail.log like
Jan 26 18:19:24 mark5 postfix-policyd: rcpt=10111, throttle=clear(a), host=iii.iii.iii.iii, from=xxx, to=yyy, size=0/999999999, quota=0/100000000, count=1/512(450), rcpt=1/3600(1757), threshold=0%|0%|0%
additional matches that should not happen do happen.
In the postfix case one should only consider lines with 'postfix/qmgr'.
In the sendmail case I wouldn't know what to do, since I don't use sendmail...
If the problem is that one does not know whether grep/awk etc. exists (with the desired features) on potentially ancient systems like Debian 3.0 etc. one should maybe include the required tools with the installation package.