mx4.vianet.ca has no MX records.
Question and response
Question
dig mx4.vianet.ca. MX
Answer
The response has no answer records.
Authority
vianet.ca. 900 SOA gwn.vianet.ca. hostmaster.vianet.ca. 1771795894 600 900 604800 900
Additional
The response has no additional records.