Does forwarding email result in an extra "persistence" of it's copy?

Question

I understand that when an email is sent from point A to B, it can persist in other locations while in transit from A to B.

When forwarding email, can this increase the extra locations where one's email can persist?

For example:

Situation 1: Someone sends me an email from their address (A) to my address (B).

Situation 2: Someone sends me an email from their address (A) to my forwarding address (C), which is setup to forward emails to my address (B).

Does situation 2 result in more locations where the email persists on servers that situation 1?

Answer 1

In some cases, yes.

Client

It depends on the MUA/client, but forwarding a message will cause a copy to be stored in that person's sent items. That counts as a copy, as does the copy in the inbox.

Outlook/Exchange can store these copies either on a local PST, on the Server, or both in the form of an OST

Server

Every MTA (server that touches the message) can store the message, and copy it into a monitoring / compliance queue, and still send the message on to the next destination.

This may be required to maintain compliance with certain federally mandated record retention laws.

Bottom line, if you forward a message, and it's routed to a network, the quantity of servers it touches increases. Any server can be configured to transparently archive a message.

Answer 2

SMTP does utilize TCP to transmit messages, so a pure forwarder should not technically need to keep a copy of the email after it is delivered since it can rely on the reliability of the protocol in which it is sending. However, we cannot speak to the effect of all SMTP implementations. One of the most popular, MS Exchange, will not hold onto a copy as far as I know unless there is a mailbox in the system for that address.