1. Use Thunderbird to delete from Inbox (or another visible folder), not Trash

If you still have the emails in the original folder (not Trash), do this:

• In Thunderbird, select a chunk of messages (definitely DOT NOT try all 100K at once; try ~1,000 at a time to start).
• Press Shift+Delete. (This bypasses the Trash and immediately flags the messages for deletion and expunge.)
• Right-click the folder and choose Compact. (This should trigger EXPUNGE to permanently remove the messages from the yahoo server.)

This usually clears them from Yahoo and reduces your storage footprint.

2. If they’re already in Yahoo's Trash, your best bet might be to move them to a another custom folder in yahoo first.

TO Do this:

• In Yahoo webmail, create a new folder (e.g., DeleteThisFolder)
• Move emails from Trash back into that folder (yes, annoying, but bear with me here)
• In Thunderbird, sync that folder via IMAP
• In Thunderbird, select messages, press Shift+Delete
• Right-click the folder -> Compact

This works more reliably than trying to delete from Yahoo’s Trash folder directly.

Thanks very much, Mike - I'll work with these recommendations and follow-up once I have some experience (hopefully can handle batches larger than 1K; there are ~150K messages that need to go away!)

1k is a first test batch, go up from there to 5k, 10k. and maybe hold there

I'm making headway on this project, however, I'm now stuck at something that might be Thunderbird-related:

I've worked out a method to expunge the Yahoo Trash folder by using Yahoo app on an android phone; it's delete trash feature isn't perfect (it deletes only a portion of the folder), but using it repeatedly has given me a method to clear the (very large) trash folder (and anything moved into the Trash folder - such as sent mail)

However,

I'm not able to manipulate the Inbox (which is my final task on this clearing adventure. The Inbox contains about 140K messages (remember, this is 15 years active use). Yahoo webmail does not work when I try to select (via search) a fraction of the inbox (such as before:1/1/2020) and move those to Trash - it "completes" abnormally quickly (a few seconds) and moves nothing. So, on to option 2:

Thunderbird has decided there are only 10K (10,000) messages in the Inbox, so when I attempt to (for example) search for emails before a date (such as 1/1/2020), those are more than 10000 messages away from most current.

Is the 10,000 message limit hard coded or is it a parameter somewhere I can change (example, 200K would suffice). I've otherwise confirmed that deleting emails in Thunderbird moves them to the Yahoo mail trash folder, and from there the method using the Android app can allow me to complete this task.

Any info on the 10,000 message problem?

Thanks again!

Sorry the noise - just a little searching yielded "export.imap.yahoo.com" serverand now the 10000 message limit appears to be resolved, so trudging forward again!

OK - progress but stuck again - I need to move/copy the profile folder to another drive - now that IMAP is accessing the (so far >200K) emails in the Inbox, it's certain that the capacity on the C: partition (which was intentionally small, leaving most storage for D: partition) will be exhausted before downloading completes. Ideally, I'd like to create the new profile (on D:) then copy the contents of the profile folder (currently in C:\....\Roaming\Thunderbird) to the new profile folder, then switch the default profile to that folder and restart Thunderbird so I don't need to reconfigure the account settings and data which is now being downloaded.

Based on what I've read so far, there is a profile management method that can be used while Thunderbird is running, but I cannot locate it.

I am searching for profile manager (for use when Thundebird is running).

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-thunderbird-profiles#w_manage-profiles-when-thunderbird-is-open

This is in a support topic which appears to be current (Last updated: 6/15/25)

I followed help -> troubleshooting information, however, there is no link (in the large tab of contents) for about:profiles. There is no search input for the tab "troubleshooting informaton".

Thunderbird (on a Windows 10 64-bit machine) reports 141.0 (64-bit)

Where can I find about:profiles?

about:profiles is in the first section, Application Basics, near the bottom of the table in the second column.

But I think that you want to close Thunderbird and copy your profile in the file system to D:, then tell Thunderbird which profile to use.

OK, just trying get through this quickly from scratch - I ended up inadvertently destroying the working profile, then started in -p mode and created a new profile on the D: drive (however, it places the profile folder in the root directory of D: even though I created a folder and believe I specified that as the intended location for the profile.

Anyway, recreated the profile and now have it updating via imap with the "export" version of imap (why didn't the profile get created with this imap server?)

Just some frustration trying get through enough of the learnig curve quickly, but think it's now working as intended.

Thanks again for your patience with this rapid-fire set of beginner issues!

Hitting two more limit problem -

1. Thundebird stopped downloading emails from yahoo inbox when exactly 100000 emails had been received into local email box. I gather this is a limitation - in Yahoo?

2. Assuming 100000 email is limit of transferring email from yahoo inbox to thunderbird's inbox folder of the same account (I do not understand why this limit?), I tried selecting all of the 100000 emails in the inbox folder of thunderbird, created a local folder, and selected "move to" expecting these 100000 emails would be moved from thunderbird's inbox under the yahoo account to the local folder. This stopped at 5000 emails. What is this limitation?

It is becoming very frustrating to solve the problem of ~140000 emails in yahoo inbox using IMAP. Is IMAP a poor tool for this? Why cannot Thunderbird process a move request instead of just stopping at 5000 emails? This is preventing my attempt to create a local copy of the 140000 emails and then delete them using Thunderbird to move the on-line emails to Yahoo Trash where they can then (with some effort) finally be removed.

Please help me understand what these limitations (100000 emails from yahoo webmail via imap to thunderbird imap inbox folder, then 5000 emails from thunderbird imap inbox folder to local folder, even though all 100000 emails were selected) are so I can find solution.

Dave

Shift-delete from the inbox is important.

I am editing a post that was published out of sequence because of moderator review:

See ThundaMike’s #1. If your goal is permanent deletion, you do not want to copy messages, just delete them permanently from the inbox.

Thunderbird’s limits: https://kb.mozillazine.org/Limits_-_Thunderbird

Yes, Thunderbird can help—but with some limitations. Since Yahoo’s IMAP doesn’t expose the Trash folder properly, one workaround is:

Create a new folder in Yahoo Webmail.

Move unwanted emails there.

In Thunderbird, subscribe to that folder, download messages locally, then delete them.

After deleting, use File > Compact Folders in Thunderbird to trigger the IMAP EXPUNGE command.

Make sure you're not just copying emails—use "Move" to remove them from the server. Hope this helps!

The process of moving emails from Inbox to any other folder (on Yahoo) is broken (at Yahoo); all other folders there can be managed and moved (including to Trash), however, Inbox appears to be irretrievably failed as I cannot perform a search (in Yahoo) specifying (for example) a date range, and move those emails to any other folder (on Yahoo); that process fails to move any data at all. Yahoo is clearly buggy!

With gratitude to the community members that have contributed to this discussion, I'm pretty sure it's time to try another IMAP client than Thunderbird, as new problems (in Thunderbird) have manifested overnight:

1. The three "move to" folders each terminated prematurely (each was intended to receive the results after select-all - probably about 140K emails, at least the 100K emails listed in the folder summary - followed by move-to a loal folder created to receive the data), and the third one (started last night after the first two terminated prematurely) contained thousands of emails that appear to be blank (no subject, no sender address, and all about the same date/time), and it too terminated (after cleaning that mess up, about 3600 emails were actually "moved")

2. The action performed was a copy, as the original source folder retains the same emails.

3. After running overnight (I'm in US), the source (myaddress@yahoo.com/Inbox) folder now *might be* complete (a spot check suggests that perhaps all 140K-or-so are there), however, the folder summary information still indicates 100000 emails (and 12.4GB storage which is signiicantly short of the actual total) I can't be certain that the source folder is complete as I don't see a way to get a valid count (which I'm sure is not exactly 100000 emails)

Fortunatly, I had previously and tediously (with use of yahoo android app) cleaned out enough other folders that my current storagre total is about 19GB, deferring the threatened immediate cut-off due in about 3 weeks, so I have some time to find another client and try that as a way to manage this server-side problem with Yahoo email.

Thanks again for the replies to my initial posting, however, it appears I will depart without any useful solution.

Tried highlighting all emails in the yahoo inbox folder and select "save" (to see how many files would be produced) - this worked until about 71K emails saved (each an individual file) then stopped with windows dialog box suggesting that the name of the file trying to save was not accepted by windows 10, unable to continue.

... sigh ...

Sounds very frustrating and I'm sorry to hear you are on yahoo. Along those lines, rather than deleting all of these messages, why not save the few messages you care about in a local folder, then get a different mail provider and bring those messages in the new account?

Some additional items along the lines of Inbox ....

> Thunderbird has decided there are only 10K (10,000) messages in the Inbox, so when I attempt to (for example) search for emails before a date (such as 1/1/2020), those are more than 10000 messages away from most current.

Your note about "export.imap.yahoo.com" is interesting, and I found it mentioned in searches, but no technical detail. FWIW https://help.yahoo.com/kb/download-email-yahoo-mail-third-party-sln28681.html

For speed reasons, in addition to using shift+delete then "compact" on the inbox, in account settings I would temporarily disable message sync for the Inbox (properties > sync) and in Settings disable "Enable Global Search". Then when you are done, you can delete global-messages-db.sqlite, reenable the aforementioned settings, and let the search database rebuild.

Sounds very frustrating and I'm sorry to hear you are on yahoo. Along those lines, rather than deleting all of these messages, why not save the few messages you care about in a local folder, then get a different mail provider and bring those messages in the new account?

In a new account other than yahoo, and abandon (delete) the old yahoo account.

I've thrown in the towel with Thunderbird for this task - the apparent 100K limit on total emails in a folder (via imap) was a barrier too large to surmount. Am now underway with EM Client which at the outset seemed to handle the >100K email inbox size (which it reported at about 140K). Currently I've got it moving emails from the giant inbox into per-year folders, which I'll then begin locally archiving and removing from Yahoo's server; this should be completed before Yahoo's unilateral terms-of-service change in mid-late August 2025.

Thanks so much for the numerous contributions to my work on this problem - in another world there would be time to explore options further...

Although this problem wasn't solved via Thunderbird, I'm going to flag this as "solved the problem" as I don't plan further work with Thunderbird to address the task at hand.

Thanks again!

Dave

Dave, did you ever use shift-delete on messages on your inbox? It seemed to be the solution.

Hi Rick - I didn't get that far (shift delete) - there was a core problem of only syncing 100K messages (as it turns out, around 140K in the Inbox folder), there were stability problems I encountered when trying move year-by-year sections of Inbox to year-by-year folders (initially to reduce Inbox size to <100K so that I could better manage the data).

I wasn't just trying purge the inbox, I was seeking to retrieve the data there, leaving only current-year email in the inbox where the account would then be below Yahoo's newly imposed data cap and the excess data would be kept offline for future reference.

Shift-delete (to remove data after copying) should not have been necessary as I was focusing on moving (not copying) sections of Inbox (selected blocks of 5K each) to other folders; as far as I can tell Thunderbird was copying (not moving as selected in the context action menu) as originals were left in place, which I was going to handle by shift-delete (to remove the originals after "copying"), however, I was not able to get that far as each move (executed as copy) stopped prematurely (<5K processed) and in one case generated several thousand empty emails in the destination folder. At that point I felt that Thunderbird was probably being applied in a load environment that it wasn't well tested for, and that's where I departed to other solution.

Thanks again for your suggestions for this project!

Dave

Thanks for the update.

FWIW, it's still quite unclear to me how you could possibly be hitting some Thunderbird limits (unless you were using drag and drop of messages - and you didn't indicate you were using drag and drop). But regardless, if had realized you're primary goal was copying or moving message rather than delete, I would have suggested using filters, which would be a much smoother process than drag and drop.

Hi Wayne, much appreciate your time and efforts to help, and yes, I didn't explain the initial problem clearly (in a nutshell, Yahoo suddenly and unexpectedly made a major change to terms of service/offer that render their email service incompatible with my use patterns over the preceding 20 years,hence an urgent/immediate need to offload and protect email history from there.)

The core problem I encountered with Thunderbird was handling an email folder via IMAP that exceeded 100K emails (unthreaded count, read or unread in total). It was that encounter (after first encountering a 10K limit that turns out would be solved by using a different IMAP server address than the one auto provisioned by Thunderbird), combined with problems in Yahoo's webmail environment itself (could not filter/select subsets of the giant inbox to cleave it into smaller folders) means my definition-of-problem was changing in real time. I didn't use drag/drop at any point, and I didn't use filters in Thunderbird (learning curve fail on my part), but I did use highlight swaths of emails and right click context menu to initiate move-to (which didn't behave as expected.)

Anyway, the email client I'm now using (EmClient) handled the >100K inbox count (so greatly simplified maniulation of the giant folder) and hasn't (at least so far) exhibited stability issues I encountered with Thunderbird in handling very large email counts. As I suspect my use case is not typical (giant email folders resulted from growing accustomed to searching for emails rather than pre-organizing in folders) and my timeframe also is atypical (under the gun due to Yahoo), I really can't fault Thunderbird nor the very helpful people that offered support here!

So, thanks again for your time and efforts on behalf of my self-imposed task!

Dave