1848494 - Files in ImapMail on Windows change even if there are no new emails

Status: UNCONFIRMED

(Thunderbird :: Untriaged, defect)

Description

[porretta.danilo]

Steps to reproduce:

• Sync an IMAP account
• Refresh your account
• Make a note of the size and the datetime of the files without any extension in the ImapMail folder (which, as far as I understand, are the files where Thunderbird stores your emails, one file for each folder)
• After a while, refresh it

P.S. I tested it on Windows, but I think this is not a problem related to the OS.

Actual results:

Almost all the files in the ImapMail folder are changed, even those that did not receive any new email.

P.S. I understand that the ".msf" files (that are usually small) can change because they contain some metadata, but here I am referring to the the ones without extension (which are usually much bigger).

Expected results:

If no new emails are received in that folder, the Thunderbird file that stores it locally should not change.

Comment 1

[Wayne Mery (:wsmwk)]

Could be your AV software?

Comment 2

[porretta.danilo]

(In reply to Wayne Mery (:wsmwk) from comment #1)

Could be your AV software?

I do not think so. It does not happen with any other file in my system (I know this because I regularly check them and I backup most of them).

This is actually problematic when you want to backup your data (as also mentioned in the bug report you cited). And, as mentioned, it happens to me to MSF files as well (as mentioned in that bug report).
But, while MSF files are "small" (a few KBs, so it is annoying to sync them every time, but it does not take much time), the actual files that contain the emails are usually huge (several GBs).

I think people do not notice this if the do not backup their data. The files only change slightly, so you do not notice that if you do not use a software that checks that they are actually different.

However, could you confirm this is not the expected behaviour (i.e., TB is not supposed to modify the files in the ImapMail folder if no new emails are received)?
I am asking this because in the Mozilla Support website some people kept saying that this is a "normal behaviour".

Thanks

Comment 3

[Wayne Mery (:wsmwk)]

Almost all the files in the ImapMail folder are changed, even those that did not receive any new email.

Now that I think about it more, I think this has been normal. Though certainly not helpful for backups.

Comment 4

[porretta.danilo]

Now that I think about it more, I think this has been normal. Though certainly not helpful for backups.

Is this something that you think should be fixed?

There are many cases where you want to use date/size to know if something actually changed in a file, so it should be something useful even for other use cases.
Moreover, it does not seem something difficult to achieve (but I am not really sure about this).

Thanks

Comment 5

[Wayne Mery (:wsmwk)]

Magnus, is there an historical reason that explains this?

Comment 6

[Magnus Melin [:mkmelin]]

I don't think so. But I also do not see it on linux.

Comment 7

[Wayne Mery (:wsmwk)]

So perhaps this is only on Windows

Comment 8

[porretta.danilo]

I can confirm the bug on Windows, but I cannot confirm whether it also affects other OSes.