Updating email mail servers

A client who I’ve migrated from BC to Treepl has two mailboxes. I’ve advised her to change the incoming and outgoing mail servers from worldsecureemail to mail.mailconfig.net on all her devices. She has the email accounts set up as IMAP and reported that “I changed all the server information over and then had a total heart attack as it looked like I lost all my folders, they slowly came back in and it started to sync them all. It’s done 3 folders and that’s taken hours and now it’s all come to a screaming halt. I seem to have to sit here and click on each folder for it to sync. Is there anyway of setting it up that it will do it all automatically. If I have to do this on the laptop and phone also it’s going to take days.”

Has anyone else had this problem? Any advise?

I haven’t had this particular issue, although, in the past when using email clients and IMAP to do mail account migrations, some users internet will choke on the data trying to be synced (I guess they are on slower/poor internet connections).

The only fix I could see if this is the issue is to somehow manually limit the amount trying to sync (which kind of sounds like what’s happening with your client anyway, with only the active folder syncing when requested).
But some email clients have IMAP Folder sync settings where you can control which folders are to be synced - or you may even be able to control this via Webmail.
Doing this you could progressively sync a few folders at a time instead of the whole account perhaps.
Alternatively, maybe they can try to connect to a much faster internet connection for this task.

Out of interest, or for anyone else reading who might be able to help, what email client are they using?

Thanks for your reply @Adam.Wilson. The source code of her latest email to me says “Microsoft Outlook 16.0”.