Before you start, have your full email address and mailbox password ready -- see Email client settings if you need the underlying server details this guide fills in for you.

Add the account

1. Open Mail, then go to Mail > Settings > Accounts and click the + at the bottom of the account list. On some macOS versions this list lives in System Settings > Internet Accounts instead -- the steps from here are the same either way.
2. Choose Other Mail Account… at the bottom of the provider list. Mila isn't one of the built-in presets (iCloud, Gmail, and similar), so this is the option to use regardless of which macOS version you're on.
3. Enter your name, your full Mila email address, and the mailbox password, then click Sign In.

If automatic setup fails

Apple Mail tries to find your account's servers on its own first. If it comes back with "Unable to verify account name or password," it wasn't able to, and you'll be prompted for server details directly:

• Incoming Mail Server: imap.mila.cx (or pop.mila.cx if you'd rather use POP3), your full email address, the mailbox password.
• Outgoing Mail Server: smtp.mila.cx, the same email address and password if it asks for SMTP authentication.

Apple Mail picks standard ports and TLS settings for IMAP/POP3/SMTP on its own once it has the hostnames above, so you shouldn't need to enter port numbers by hand at this step.

Finish and verify

Choose which apps to sync for the account (Mail, Notes, and so on) and click Done. Send yourself a test message, and check that the account shows as Online in Mail > Settings > Accounts if anything looks stuck.