I was flagging a thread with a similar issue - It looks as if your Mail exchangers are rejecting initial connections in some cases for a number of days.
@AnnaT Can you go into Webmail using you laptop and on one of the affected mails click the menu button and then show original.
If you can paste the source here:
And screenshot the Relay Information - Like this:
Note: I'm no longer a Virgin Media customer (through circumstances, not choice) So your list of servers will not be the same as mine. This will help determine where the problem lies though.
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