[Arch-TK]

How did you get 6?

I run my own infra and on my end I see 1 permanent server side copy and 1 temporary local copy.

[melicerte]

1. local copy of the file on the sender computer

2. local copy in the send item once sent

3. a copy on the sender email server

4. a copy on the receiver email server

5. a copy on the inbox of the receiver

6. add one if the file is saved as a local copy on the sender computer

And this does not take into consideration backups (like local backups and email server backups). Also, the number increases obviously by the number of recipients (points 4, 5 and 6).

(edited for layout)

[Arch-TK]

I don't know why you keep counting two server side copies for each side.

It's 4 total if both sides cache the file indefinitely and 2 otherwise.

edit:

Okay, I see, you are talking about physical files.

Sure then there might be up to 6 copies of the file.