IMAP: "UID COPY failed", POP: connection timeout

IMAP: "UID COPY failed", POP: connection timeout

Hello,

 I like to use Zoho Mail, and until yesterday there was no problems with it. The problem is that yesterday I found out that Zoho since some time allows to use IMAP as the client protocol, so I wanted to check it out.

 I've deleted my old POP mailbox here on my local Thunderbird client (this was a bad thing to do), enabled IMAP in the Options and created new IMAP account in Thunderbird. Then my mail started to download and it all appeared it's working.

 Problems started when I wanted to create some filters in Thunderbird - I was getting errors from the server: "Mail server for account <myaccount>@zoho.com response: UID COPY failed.". I didn't even notice that suddenly part of my mail was doubled; now I have two the same email messages from some senders. My further tries to fix filtering resulted in even further doubling, and now I have 4, 6 copies of some mails, in the mailbox. But that's not the problem.

 I've removed the IMAP version of my account in the Thunderbird client and wanted to go back to POP. I've created the POP account, the mail started to download. But now, after downloading ~1500 mails, and having ~400 mails to go, I'm getting the "connection timeout" error everytime I want to download the last ~400 mails; When I click on "receive email", Thunderbird says there are ~400 mails to be downloaded. It starts to download them, and after 73 mails it hangs; few minutes later there's this connection timeout error message again. It seems that there may be a problem with one mail being processed by the Zoho server, is this possible? Maybe it's linked with some data corruption error, which I triggered by using Thunderbird filters when checking the IMAP protocol?

 Anyway, on the other machine (smartphone), mails are working OK. There's just the problem when I want to re-download all mails through POP. I'd like to use the IMAP version, but it's not compatible with Thunderbird, which I'd like to use, so I'm OK with POP.

 Thanks for any info on this and sorry for such long post.

- a1