Re: Rejecting message/partial?

[Wichert Akkerman <wichert@wiggy.net>]

Previously Martin Schulze wrote:
> Section 5.2.2.1 of RFC2046[1] describes "Message Fragmentation and
> Reassembly".  This technique may be used to deliver large files through
> the Internet without delivering them in one large mail.  For example,
> sending a 3MB large picture could be splitted into three 1MB chunks.

A sensible approach. Some Sun mailsoftware used to have the same
capability but that predated this RFC if I remember correctly.

> Research has shown that this technique only seems to be supported by
> Outlook Express, though.

In other words the majority of people sending mail on the internet
can use it.

> Do you feel it would be good for mail filters to reject all such
> messages?  I.e. reject all parts of partial messages?

Same rules as for a NIDS would should apply imho. In other words:
defragment, check complete message, and then either resent the
original posts or bounce them. Optionally you can optimize this
by only checking the first fragment, but that will make your checks
less accurate.

It is a useful feature, so blindly reject all its uses does not
sound like a good approach.

Wichert.

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