smtp01.uptodate.com has no MX records.
Question and response
Question
dig smtp01.uptodate.com. MX
Answer
The response has no answer records.
Authority
uptodate.com. 86400 SOA cbru.br.ns.els-gms.att.net. rm-hostmaster.ems.att.com. 2006092548 10800 5400 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0