At this time Sendmail does not recommend the deployment of SRS or other
mail forwarding modifications by forwarding services due to the risk of
incompatible changes with more reliable cryptographic solutions.
I have to partially agree with them. The current SRS syntax is not
compatible between implementations (I've found at least 3 different
SRS syntaxes out there in different technical specs or implementations)
and do not make it easy to find original address.
If SRS was part of the standard framework which explained how original
address can be found in the rewritten MAIL FROM (or MAIL FROM that
undergone other changes such as additional of SES signature) then
cryptographic solutions could be written to ignore the rewriting
and find and use original address.
---
William Leibzon
Elan Networks
william(_at_)elan(_dot_)net