It is possible that instead of relying on RMTA to record the SMTA IP
address, we can do a DNS MX lookup of sender email address to get the
MTA IP address at the sender side. However, this indeed means that if
sender side uses different MTA servers for incoming and outgoing
messages, they need to be in sync about state of outgoing message queue
(for example, shared file systems).
Gee, that's a good idea. Imagine a shared filesystem supporting the whole
email infrastructure for millions of customers!
I think there is some misunderstanding. Note that this is for supporting
MTA clusters. Shared file systems/NFS/Replications are used in today's MTA
f.a.n.finch <dot(_at_)dotat(_dot_)at> http://dotat.at/
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