-----Original Message-----
Dave Goodrich wrote:

> We use MailScanner because it offers additional tools, delivery options, 
> routing, and filtering above clamav. We also do not have issues with the 
> clam daemon that some have had. Julian is exceedingly responsive to his 
> community, the level of support and help on the MailScanner is second to 
> nothing I have seen in Open Source Software.

::snip::

> Clamav is great, MailScanner just makes it even better.

MailScanner has a design flaw that can not be overlooked.

By not being a Milter, it does not operate during the SMTP conversation,
meaning you can not "reject" during the conversation.  Because MailScanner
is a post-conversation processor, you have to either generate a separate
bounce message to return to the sending server which will undoubtedly just
sit in your outbound mail queue due to forged or invalid sender addresses...
Or you silently discard a message after fully rec eiving it (which does not
tell the sending server that the message was unwanted.  In addition, you
have no option but to fully receive the message (and expend the bandwidth,
disk space, and other resources required to receive it), before deciding you
don't want it.

Better to use a Milter, because a Milter can reject during much earlier
parts of the SMTP dialogue, such as at the EHLO/HELO, the MAIL FROM, the
RECPT TO, and so on... Before you commit to receiving the body, for example.

MailScanner is nice, as it is highly customizable.  But if you want that
flexibility PLUS the advantages of a true Milter, you should look at
MIMEDefang.

And MIMEDefang can work in conjunction with the Clam milter, with Clamd, or
with clamscan (or any combination of those 3), in addition to other
scanning/filtering options "out of the box".

Ken
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