Have you checked the state of the folder on the server? Is it possible that the message was trying to tell you about that folder instead?

I don't know for sure what the local file size limit is. At various times I've read that it is 2GB, 4GB and unlimited. And who knows what limits apply at the server?

But why keep even that much (2.5 GB) in the Inbox? I keep my Inboxes empty, by filing useful messages into other folders and deleting the cruft. My Inbox is my "to do" file.

Hi Zenos,

Thanks very much for your reply.

I just checked the folder on the server (by logging into Hotmail/Outlook Mail directly in my browser) and all seems fine as messages are still coming in and there is no indication that the mailbox is full.

I agree that my inbox should be cleaned out and will hope to get there over time. It is not currently the best time for me to go through the 6 years of emails - but one day!

Some updates:

• I just deleted another several thousand old emails and compacted the folder, which brought the folder size on disk down to 1.8 GB.
• I noticed that after I did this, it said it was "Downloading X of 4184 in All Mail". It went through this for a while until it finished all 4184. However, both during and after this time, I have no idea what it was downloading as no messages (either old or new) were showing up in Thunderbird.
• For a few times, when I tried to 'Get Messages', Thunderbird simply said 'No messages to download' in the bottom left. This seems strange as it has yet to ever download the messages August 11 or later. No error message appeared.
• On other instances when I try to 'Get Messages', I am still getting the same error message: "The folder Inbox is full..."

Zenos said

I don't know for sure what the local file size limit is. At various times I've read that it is 2GB, 4GB and unlimited. And who knows what limits apply at the server?

2Gb was a limitation on certain Linux and Mac 32bit operating systems and windows using the fat file system. It was a limitation brought about by the operating system not being able to address file locations over 2Gb with a 32bit integer. Windows implemented the fat 32 file system which increased that to 4Gb with Windows 95. So in the Windows world the limit has been fgone for relatively longer that in Linux where 32bit distributions were popular will into this millennium.

We still see FAT and the 2Gb limit it imposes on USB thumb drives. So it may be some portable Thunderbird still has a 2Gb limit based on the file system used.

Thunderbird itself has had a 4Gb limitations on local folder sizes. This limit was side stepped some years ago for IMAP mail accounts. By implementing 64bit message keys. These message keys have traditionally been recorded using 32Bit integers and as a result addressing more than 4Gb is not possible for non IMAP accounts.

I have been following Bug 462665 for years. (it was closed as complete in2012). The only part of the elimination of the 4Gb limit I can find still outstanding is on QNX and I really doubt that will ever be done. It hardly wins a popularity contest as a desktop operating system.

So while I have no doubt that there be bugs in there, the hard limit can be considered a thing of the past, with the last major user interface component landed on the 1st August in Bug 789679

Based on that Thunderbird 52 will be the first Thunderbird version to actually be limit per folder free.

Thanks for your reply Matt. Sorry if I missed it but was there any recommended steps for me to take to try resolving this issue?

FYI I since deleted more emails to get my inbox size on disk to 1.6 GB but am still getting the same error message.

This issue remains unresolved and I still have not been able to use Thunderbird since.

You shouldn't have an "All Mail" folder on your desktop. Are you referring to a server-folder or do you use IMAP?

If it's an POP3 account, do you "leave messages on server - until I delete them"? (account settings / server settings) Hopefully not.

Create a backup of your profile if you don't have one.

With Thunderbird NOT running open your profile, go to MAIL and your account:

• Rename INBOX to OLD_BOX or whatever
• Delete INBOX.msf and Popstate.dat

Start Thunderbird

EDIT If you have all your messages also on the server I suggest you zip them into a file and download. There should be an option on the server to do so. Otherwise all your old messages will be downloaded again.