Local backup and remote mail exchanger are options for the MX Entry for a domain in cPanel. With this, the server knows the way to handle your incoming emails.
The meaning of separate options is:
- It is recommended to select the option “Automatically Detect Configuration”, if you have a particular setup that needs to be openly displayed.
- Local Mail Exchanger: It manages all mails sent from the server to this domain locally; i.e. – it delivers them to the mailbox located on the server instead of remote mail service.
- Backup Mail Exchanger: It manages all emails like a remote mail exchanger, except in the case, the remote service is unreachable. If that’s the case, it manages the mails similar to a local mail exchanger. (For example, if Office 365 is the mail service for your domain, then it sends the emails to Office 365’s servers similar to the remote mail exchanger. If for any reason, Office 365’s servers aren’t accessible then it delivers the mail locally, similar to the local mail exchanger option.)
- Remote Mail Exchanger: It manages all mails sent to your domain remotely; i.e. – delivers them to the mail service searched by the domain’s MX record. (For example, if Office 365 is your mail service, it will deliver the emails to the mailbox on Office 365’s servers rather than your local mailbox.)