mail-server.swiftrfp.com has no MX records.
Question and response
Question
dig mail-server.swiftrfp.com. MX
Answer
The response has no answer records.
Authority
swiftrfp.com. 86400 SOA dns1.swiftrfp.net. admin.swiftrfp.net. 2023011244 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0