Senn-torr
The "taur" is probably the same root as in "Taurus" and "el Toro"¹, which I've only ever heard said like torr, so I say it the same. The first part I don't think is ever said anything other than "senn" right?
¹I can't back that up, since they mean bull not horse and I have no sources. We do see the same root pop up in "Minotaur" from the same language though, and that is a part bull part man.
Your description has made me realize... J.D. Vance is Starscream.
They do, yeah, and the email is RoundCube from memory? I have a personal Nextcloud and really can't fault them for using it in place of building Yet Another in-house drive solution - it's good software, bront.
For people who want custom domain support, as well as SMTP/IMAP, but still euro-based, Nubo may be more what you're looking for if you're OK with dealing with a newer company.
That is a great theory and until an excited nerd tells me otherwise it's what I'm going to choose to believe (albeit without telling anyone else just in case)