Downloaded folders much larger than on server

User Help for Mozilla Thunderbird

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Joined: July 30th, 2003, 5:06 pm

Post Posted October 24th, 2018, 1:11 pm

If your goal is to share email having offline folders does nothing for that. Remote folders are what other users can access, if its either a shared account (what you seem to be using) or configured as a "public folder" (requires admin to set ACL's to let people access a folder that is not in their account).

Offline folders are a poor backup as they can get automatically wiped when you start Thunderbird if you sync with trashed remote folders. If you want a local backup I'd suggest disabling offline folders, and use a message filter to automatically copy your personal inbox and sent folders contents to folders in Local Folders. Or use something like IMAPSize which can do automatic incremental backups to .eml files. By incremental I mean it doesn't backup a message again if its already backed up. It can't be configured to run as a windows service but it supports command line arguments so you could do something like change your TB shortcut to point to a 2 line batch file. The first line runs Thunderbird, the second runs IMAPSize.

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Joined: September 9th, 2018, 1:41 pm

Post Posted October 24th, 2018, 1:44 pm

IMAP is not really designed for a computer to have a good backup of the emails. It is "kinda" possible, but lots of strange things happen. If you can switch to using POP3 (POP3 cannot have / access multiple folders on the server - only the inbox exists as far as POP3 is concerned) local backup is easy and works consistently.

In order to use POP3, you would need to find the name of the POP3 server for your email provider, and setup everything new in a new Thunderbird profile. Note - make sure you have the option to "leave messages on the server" as yes.

Posts: 17
Joined: March 27th, 2017, 8:38 am

Post Posted November 29th, 2018, 3:53 pm

I have something interesting to add. As I said, I often run multiXpunge to ensure my folders are all compacted. As I was doing it earlier today, I noticed that the status in the bottom left corner indicated that the account was "downloading message header Y of X" where Y was much larger than X. A screenshot is at my other post on the Mozilla site ( ... er-1177002) down at the bottom. Is this possibly an indication of what's going on here?

Posts: 17
Joined: March 27th, 2017, 8:38 am

Post Posted January 8th, 2019, 2:28 pm

I have some more information on this issue. As I have multiple computers working with the same IMAP accounts, I have been waiting to see if one will "inflate" the files while the other remains "uninflated". My laptop inflated yesterday so I found a email store file to compare from each system.

The IMAP folder contains one email. When I open the corresponding files, the uninflated one looks correct. The inflated one, on the other hand, has the entire email repeated four times within the file. The only difference I notice from one of the repeats to the next is the date following the "From" line at the very top of each.

It looks like Thunderbird is just downloading the same email over and over and saving repeat copies into the file connected to the IMAP folder.

Anyone have any ideas? Thanks!

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