China Mobile 139 Mail (@139.com): Enable IMAP/SMTP + Set Client Password (You Define, Not Auto-Generated)
Complete setup for China Mobile 139 Mail (phone number + @139.com) — enable IMAP/SMTP at webmail [Settings → Account & Security] + 'set' a client password (you define it, not system-generated). Paste the client password into the Laifaxin password field (not the login password).