Yandex for a domain, how to painlessly transfer users from pop3 to imap?

Question

Yandex

I decided to transfer corporate mail to Yandex and ran into a problem. Yandex disabled pop3 for new mailboxes and did not say anything about it anywhere. In all manuals, pop3 is present, but I didn’t find it anywhere for new boxes. Because the transition has already been made for the director and the secretary - there is no turning back. In mailers, users have pop3 configured. Letters about 3-6 thousand. How to transfer mail from pop3 to imap without losing emails in thunderbird? Copying takes a very long time, there are about 50 users.
And I would like to warn other people against switching to Yandex for the domain, because according to information from Yandex technical support, they are going to disable pop3 altogether. I wonder if they will warn or just turn off?
upd
They have another surprise, until you go to the user box through the web interface and accept the agreement, the mail is not sent. That is, you need to go into each mailbox, subscribe, accept the agreement and enter the captcha.
Yandex, why don't you warn about all the pitfalls?

Answer 1

And they will do it right, this old slag pop3.
Only copy letters - connect a new mailbox, select letters, drag with the mouse.
Let users drag and drop their emails individually, is that a problem?
A couple of minutes and everything works.

Answer 2

But just switching the protocol in the account settings in TB does not help, does it?
And pop3, it seems, is not missing, but disabled by default. https://mail.yandex.ru/#setup/client