It had been so long since I created a profile i decided to go through the steps again. There is a button to choose anoter relay.

And here is a lis https://chatmail.at/relays

It looks like DeltaChat is a differemt email domain than Arcane. I am not sure if Delta has multiple or if it always the same one though. I do believ you can bring your own email. It just is nice that it does this in my case to onboard less tech savvy family and friends.

I use a fork of the DeltaChat client called ArcaneChat. I like it. It is easy to setup and to get others into a chat. You just provide a name on startup and it automatically creates an arcane email account for you. Moving it to a second device is as easy as using the app to pull up a QR code or getting a code it produces. Making chats with other people is similar. You can scan a QR code or send an invite link.

Also has plugins. I have a chat with an editor app so everyone in my household can add to the grocery list for instance. But there are plugins for games, rss feeds, and bridges to other platforms though I havent used these so im not sure how well they work.

My complaint and the others in my household is notifications. You might send or receive a message but wont get notified until an hour or two later. That said the very latest arcane chat does add a new setting that is supposed to help with that but i havent been on it lomg enough yet.

Also, to my knowledge you cannot lock the app itself like Signal can.

I am fairly certain you do not need to provide an email address. It creates one for you automatically. At least that is how ArcaneChat (a fork of DeltaChat) works.

ArcaneChat also supports multile profiles and it looks like thay feature has made its way into Delta now.