Mail Exchange (MX) Records
A Mail Exchange (MX) record is used to identify an email server for the domain so that other servers can send messages to it.
- in typical network, multiple servers are installed to provide redundancy
- each one is represented with an MX record
- each server record is given a preference value
- lowest numbered entry is preferred
- the host identified in an MX record must have an associated A or AAAA record
- must not point to a CNAME record