Problem using IMAP as an intermediary to copy folders

[W Postelmans]

I use Win10 (fully updated) and TB 38.3.0.

I need to copy all folders from a TB email client to a Windows Live Mail email client.

WLM does not seem to be very supportive to non-MS email clients; using an IMAP account as an intermediary seems to be the only solution to my problem.

I defined a not-used IMAP account in TB (and in WLM), created in TB a special "transfer" map in the INBOX of that IMAP account, and then started copying (using "drag and drop") the (1000+) maps from "Local Folders" into that "transfer" map. Some of these maps in Local Folders contain thousands of mails.

Each "copy" took a long time. But most copies seemed to work fine. But a few times the "copy" stopped working without telling that it was interrupted or showing an error message.

Because I copied the maps in bunches of 5 to 10 (in reality many more because some of the copied maps contained sub-maps), and because many maps contained a lot of messages, it was almost impossible to, if not during many hours constantly staring to the screen, 1) see if TB had correctly finshed or 2) it had prematurily stopped copying.

But I discovered that TB prematurily stopped copying each time it was copying a message that was to big for the mail provider (my provider accepts mails up to 20MB). Also many other email providers impose a limit on the maximum number of bytes a mail can contain. When trying to "send" such huge message, the sender gets an error message from the mail provider that the mail is to big and that it was not sent to the destinee.

Each time I tried to copy such "to huge" mail, TB reproduceably interupted the "copy" without notifying the user.

I do NOT say here that this is the ONLY reason why sometimes the copy of folders into a folder in the INBOX stops working, but this definitely looks like a bug!

Will this issue be resolved please, or if that is to difficult, maybe showing an error message that includes the foldername and message title of the message that could not be processed, so that the user sees why and when it had stopped copying?

[DanRaisch]

This forum is not run by or formally associated with Mozilla. We're an independent user-helping-user community.

[tanstaafl]

Please file a bug report at https://bugzilla.mozilla.org/ if you think you found a bug.

You could try using a utility such as IMAPSize to copy the messages to a folder on a IMAP server, instead of using Thunderbird. The simplest solution might to be try a different email provider. Gmail supposedly supports 25MB attachments, and Mail.com 50MB attachments.

[W Postelmans]

Thanks for the reply. Suspected bug filed, see "https://bugzilla.mozilla.org/show_bug.cgi?id=1235104"

[wsmwk]

Drag and drop is a slow and troublesome mechanism for mass moving of mail. A filter should be smoother.

[W Postelmans]

wsm, thanks for your reply.

Using a filter seems to be an easier option at first view, but I don't think that using a filter I can maintain the tree with folders and subfolders, and ensure that in the destination box the "filtered" messages are placed in the correct folders. I think one cannot apply a filter to only one specific folder. Ot do you know about a "trick" that could work?