Android
Add a New Account auf Android
Android treats every account, whether Google, Exchange, or a personal IMAP/POP3 mailbox, as a separate sync source. Contacts, calendar entries, and mail only appear on your device once the account is registered under system settings and linked to the matching sync service.
To add one, go to Settings ➔ Passwords & accounts ➔ Add account ➔ Choose an Account type and follow the instructions on screen. The available account types depend on what is built into the system and which apps are installed. By default, Android offers Google, Exchange, Duo, and personal IMAP or POP3 mail accounts.
Once an account is added, sync toggles for contacts, calendar, and mail usually appear automatically inside the account settings. If sync still fails after adding the account, the issue is often a wrong password, an expired app-specific token, or a sync toggle that got switched off rather than a missing account.
If you only need mail on one device without contact or calendar sync, a dedicated mail app can be a lighter alternative to adding a full system account. Adding unnecessary accounts increases background data usage and battery drain, since each one syncs independently in the background.