Editing MX record (section)

===Load distribution===
The standard approach to distributing a load of incoming mail over an array of servers is to return the same preference number for each server in the set. When determining which server of equal preference to send mail to, "the sender-SMTP MUST randomize them to spread the load across multiple mail exchangers for a specific organization", unless there is a clear reason to favor one.<ref name="RFC5321">RFC 5321</ref> 

An alternative approach is to use [[multihomed]] servers, where the one host returns several IP addresses.<ref name=balance/> This method places the burden on the DNS rather than the SMTP-sender to perform the load balancing, which in this case will present a list of IP addresses in a specific order to the clients querying the A record of the mail exchanger. Since the RFC requires that the SMTP-sender use the order given in the A record query, the DNS server is free to carefully manipulate its balancing based on any method, including [[round robin DNS]], mail server load, or some undisclosed priority scheme.