I have a Windows 10 machine, have been using Thunderbird and pobox for years. In case you're not familiar with pobox, it is a mail forwarding service; I pay for an email address and they forward email to up to three servers. I've thereby kept the same email address for a very long time, just changed the address(es) they forward to as I change ISPs, etc. At some point I quit using my ISPs server for my email and just used the one at pobox.com. Pobox was purchased by Fastmail, and so they have some new server names; my old ones have continued to work on my current system. I use POP3 instead of IMAP because I want the email on my machine, not on a server somewhere. I configured Thunderbird to do this long ago, and so I don't remember details; I've been depending on being able to extract any needed information from its configuration. I am confident I have the password correct; I can log into the web interface to my email, and the password works there. My new machine is a dual-boot Win11/Ubuntu; my plan is to use the Ubuntu machine almost exclusively and only boot Win11 when necessary. I want to move email operations to the new Ubuntu machine. I've read info on moving Thunderbird; I find the profiles on the source machine, move up two directory levels, find the equivalent directory on the new machine, copy with replace. I found: c:\Users\name\AppData\Roaming\Thunderbird on the Win10 machine, and Home/snap/thunderbird/common/.thunderbird on the Ubuntu machine, so I copied the files from the first to the second. Having done that, when I start up Thunderbird, it displays a page saying "Set up your existing email address". If I do that, of course, it will create a new profile, and I still won't have the old one. I've tried creating it manually, but (a) I don't know how I will then merge it with an old profile and my thousands of email messages, and (b) I'm having trouble figuring out the incoming and outgoing server settings. I remember struggling with that back on Win7 or whenever it was. Anyway. Anyone got suggestions on what might be going wrong here?