It would be helpful to see what, if any, error code is returned by the SMTP server in this situation. From a desktop or laptop device open a Command Shell in Window or otherwise a Terminal. and enter the following where username:password is replaced with your email address and password, i.e. firstname.lastname@example.org:Y54kpX5g:
curl -v smtps://smtp.virginmedia.com -u username:password
Do not post the resulting output here but instead review it for possible reported causes or post just the VM error code here; choosing to ignore this advice and posting the output here unredacted or incorrectly redacted may reveal your email address, password and / or public IP Address.
I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more
Have I helped? Click Mark as Helpful Answer and solved, or use Kudos to say thanks