How do I add IMAP/SMTP for a custom domain?

Your domain or IT policy requires classic IMAP/SMTP (no Google/Microsoft OAuth in the wizard).

Step 1 — Choose IMAP path
After entering the address, if the wizard does not start OAuth, you land on the manual IMAP/SMTP form.
Step 2 — Fill server fields
Incoming (IMAP) host/port/SSL and outgoing (SMTP) host/port/SSL. Many domains are pre-filled when recognized.
Step 3 — Authentication
Use the mailbox user name (often the full address) and password or app-specific password if your provider requires it.
Step 4 — Test
Use the wizard’s test action before saving. If SMTP fails, you may still receive mail but see “send not verified” until SMTP is fixed.