watchNS/messagelabs.comについて、ここに記述してください。

"*.messagelabs.com"というドメイン名があって、MXレコード（だけ）が定義されている。

$ dnsq any \*.messagelabs.com dns1.messagelabs.com
{{{
255 \052.messagelabs.com:
505 bytes, 1+2+5+18 records, response, authoritative, noerror
query: 255 \052.messagelabs.com
answer: \052.messagelabs.com 3600 MX 20 cluster6a.eu.messagelabs.com
answer: \052.messagelabs.com 3600 MX 10 cluster6.eu.messagelabs.com
authority: messagelabs.com 86400 NS dns3.messagelabs.com
authority: messagelabs.com 86400 NS dns1.messagelabs.com
authority: messagelabs.com 86400 NS dns2.mlabs.net
authority: messagelabs.com 86400 NS dns4.mlabs.net
authority: messagelabs.com 86400 NS dns5.messagelabs.com
additional: cluster6.eu.messagelabs.com 900 A 195.245.230.51
additional: cluster6.eu.messagelabs.com 900 A 85.158.136.83
additional: cluster6.eu.messagelabs.com 900 A 85.158.138.179
additional: cluster6.eu.messagelabs.com 900 A 85.158.139.163
additional: cluster6.eu.messagelabs.com 900 A 193.109.254.3
additional: cluster6.eu.messagelabs.com 900 A 193.109.255.99
additional: cluster6a.eu.messagelabs.com 900 A 216.82.251.230
additional: cluster6a.eu.messagelabs.com 900 A 85.158.136.83
additional: cluster6a.eu.messagelabs.com 900 A 85.158.139.103
additional: cluster6a.eu.messagelabs.com 900 A 193.109.254.3
additional: cluster6a.eu.messagelabs.com 900 A 195.245.230.51
additional: dns1.messagelabs.com 86400 A 194.106.221.36
additional: dns1.messagelabs.com 86400 28 *\002\014\350\000\024\001&\000\000\000\000\000\000\0006
additional: dns2.mlabs.net 86400 A 85.158.137.227
additional: dns2.mlabs.net 86400 28 *\002\014\350\000\003\001e\000\000\000\000\000\000\002'
additional: dns3.messagelabs.com 86400 A 117.120.16.235
additional: dns4.mlabs.net 86400 A 216.82.242.229
additional: dns5.messagelabs.com 86400 A 216.82.248.39
}}}