Spf max dns queries MTA option

SPF MTA options: (integer)
The  MTA option specifies the maximum number of DNS queries per SPF check. The default is 10, which accords with the requirement in Section 10.1 of RFC 4408 (SPF). (Setting this option to a value above 10 thus violates the RFC 4408 requirement.)

See also:
 * SPF MTA options