webmail.optonline.net has no MX records.
Question and response
Question
dig webmail.optonline.net. MX
Answer
The response has no answer records.
Authority
optonline.net. 900 SOA authns1.cv.net. hostmaster.cv.net. 85378 7200 600 604800 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0