Email accounts

Each account filters the inbox to mail delivered to that address, and sets the address your replies are sent from.

one.com settings

A direct account signs straight in to one.com — no forwarding, no Gmail involved. Use the mailbox’s own password (or an app password if you have two-factor on).

Incoming
imap.one.com · port 993 · SSL
Outgoing
send.one.com · port 465 · SSL

Username is the full email address. Gmail-routed accounts still work too — detected Gmail send-as addresses: none yet.