> > The *ONLY* safe way to handle these situations is to > > canonicalize every message that passes through your mail > > server by calling "action_rebuild()" in filter_end.
> Is there any harm in doing this? Potentially, but not as much as could be caused by not doing it. Some messages which are badly constructed could have sections stripped out, or the whole message trashed, but then they were badly constructed, and by definition this is non-standard and a potential risk. > Does it take a lot of CPU? Yes, if the message is complex and/or large, but not as CPU-intensive as virus scanning. > Will it break digital signatures? Possibly - but then most digital signature systems encapsulate the whole message as a single attachment, and the public certificate of the sender as a separate attachment, so there shouldn't be any impact if the signature system is a decent one. > It sounds like a good idea, but I'm afraid of potential downsides. By using such a system, there will undoubtedly be some messages which are corrupted because they have an invalid structure. If these come from a valid source using a badly-behaved e-mail client, you will have enormous problems in coping with it. On the other hand, if you attempt to correct the problem at your end, they have no incentive to fix their software.... Best Wishes, Paul. __________________________________________________ Paul Murphy Head of Informatics Ionix Pharmaceuticals Ltd 418 Science Park, Cambridge, CB4 0PA Tel. 01223 433741 Fax. 01223 433788 _______________________________________________________________________ DISCLAIMER: This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to which they are addressed. If you have received this email in error please contact the sender or the Ionix IT Helpdesk on +44 (0) 1223 433741 _______________________________________________________________________
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