Migration Assistant for XP to Mojave

My brother is about to buy an iMac and would like to transfer all his data over from his old Windows XP machine. Apple's article, "Move your data from a Windows PC to your Mac" (https://support.apple.com/en-gb/HT204087) specifies that Migration Assistant only works with Windows 7 and upwards. But I have read elsewhere on the Internet that it works with XP too. But is that old information?

In Apple's article, it specifies downloading a specific version of Windows Migration Assistant depending on what MacOS you have. I assume my brother's new iMac will have Mojave of course. So is it the case that there just is no Windows Migration Assistant to transfer from XP to Mojave, whereas in the past there did exist a version that could do XP to some older MacOS? My brother's XP is on its last legs, so there is no chance to upgrade to a newer version of Windows.

Am I out of luck with using Migration Assistant to help him? I know that the Apple Store, as well as e.g. Best Buy, will do the transfer for us using their methods. I could of course transfer FILES over easily myself (e.g. via a direct Ethernet connection), but it is things like the POP3 email folders and messages in Outlook Express on my brother's XP, iTunes music, Internet Explorer bookmarks, etc. that I don't know how to do myself.

By the way, I need to set up his MacMail as POP3 (instead of IMAP) as well because his account on his email server doesn't have those folders or old messages. Then I need his MacMail to sync with his almost brand new iPhone too, also as POP3, and then have MacMail and iPhone Mail stay in sync, something he could never do between his XP and his old iPhone (or his new iPhone the last month since he bought it).

(By the way also, I could not find an answer to this question in Apple Communities, so I'm posting this question.)

Thank you for any help anyone can provide!

Gary