Consider either of the following to help troubleshoot the issue:
open a command shell / terminal window and enter the following command for your operating system where username:password is your email address, colon, password, for example firstname.lastname@example.org:Xy3a2siz: Windows 10
This told me that I had a problem with the XBL setting. I then updated this to unblock it
Took about an hour for the change to filter thru and then everything started to work ok.
Seemed to be an app I had loaded on my Firestick. Reset Firestick to factory settings and all ok.
Thanks Very Insightful Person for pointing me in the right direction
Try Ping smtp.virginmedia.com from a command prompt to see if you have any blocks. You should see 4 pings and 4 successful replies
The XBL listing does not normally cause an outright block, although it does make bounces more likely. Blocking normally happens if you are on the SBL - or more precisely the CSS (Composite Snowshoe Spam) list.
I'd also point out that the 'block' is not at connection time, it's when the client tries to authenticate with VM's server. Thus the ping test is not a valid test.to prove that you are blacklisted.
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