Why don’t I see California?

Upvoted because you came back to put in the solution

Look at ISPConfig.

It isn’t simple but has all of the services you require:

postfix (SMTP)

dovecot (IMAP)

LMTP

MySQL databases for management

Web-based management interface

deleted by creator

Too late; mine is already running Debian Bookworm

Kaiju: “Where is my egg?!?”

“Ukraine started the fight when they hit back.”

A lot of places no longer have staff that understand email systems or routing.

Even technically-inclined Universities like Purdue have abandoned their on-campus email systems and now rely upon Office365 and GMail.

The container is regarded as a single unit; if a server inside the container fails the functions of that server are offloaded to another available server and it is taken out of service.

Once enough servers in a container are offline the entire unit has all computational load offloaded to another, identical container with sufficient capacity.

Then the now-offline unit is retrieved and serviced; probably a ground-up rebuild of all components.

… but I do like the idea of some dude in a wetsuit trying to replace a memory stick.

Completely believable.