Is there an error code in the bounce message?
Alternatively try the following
Click Search
Type cmd and press enter.
In the black box that appears enter the following
C:\Users\timdu>curl -v --stderr - smtps://smtp.virginmedia.com -u username:password | findstr VM
For username and password use your VM email address and VM password e.g.
Post the output only e.g.
< 525 5.7.13 Authentication Denied (VM304)
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