Shevek wrote:
First, you cannot add SRS to a 64-character local part.
Second, SES is added by the original MTA only, whereas SRS has to be
added
by ALL forwarders in the world.
By your description below, this is false. SES has to be added by the
original MTA AND all the forwarders.
Sorry, hat my example was not clear enough. By "ses-hash" I meant the hash
added by example.com and not by the forwarder. The forwarder only has to
prepend "@forwarder.com:" and he must leave anything after the colon
untouched.
For example if example.com sends MAIL FROM:
<John(_dot_)Smith-ses-hash(_at_)example(_dot_)com>, then the forwarder just
has to
prepend
his domain name:
MAIL FROM: <@forwarder.com:John(_dot_)Smith-ses-hash(_at_)example(_dot_)com>
You can't add this to a 64 character local part for the
same reason that you can't do SRS in a strictly
64 character local part.
The forwarder does not change the local part! (The source routing does not
belong to the local part.)
The overheads in the two cases are almost identical.
Simply prepending "@forwarder.com:" is quite less overhead compared to:
- check if the local part is short enough to add SRS
- check if there is already SRS prepended
- get the current time
- calculate the hash
- encode to timestamp and the hash
- prepend the result
This protocol requires modification both on the forwarder
and on the original MTA.
The original MTA does not have to modify anything. SES is optional. But
without source routing SRS would be mandatory.
Roger