Why can't Virgin/O2 email me?

[#1]

Virgin/O2 have been sending me email links which never arrive. My account with them has postmaster@xxxxx.plus.com as the registered address - wherever possible I've changed this because it seems that some commercial servers don't like it.
Today I rang the helpline to change/update the email address to myname@xxxxx.plus.com. To validate that new address they sent me an email to the new address, which also didn't arrive. They tried several times. I pointed out to the helpline that I'd received other emails whilst on the call, but not theirs. They suggested I wait a bit. Still nothing after 5 hours.
What could be the problem?

[#2 · Accepted solution]

I am a VM Internet customer and we do receive account & billing emails from VM at: <name>@<account>.plus.net

When VM/02 changed the email details are you quite certain they re-sent the contracts / documents ?

Have you used the email portal to make 100% sure the messages from VM/02 are not being diverted to spam on the server ?

Either :  https://webmail.plus.net/ or https://webmail.greenby.com/

[#3]

Thanks - they are in the Greenby webmail spam folder. The messages are now timed out, but I've clicked 'not spam' on one of them. Hopefully that will fix it. Actually there are one of two things in there which shouldn't have been blocked from delivery.
I'll make a note of the Greenby webmail address too.

[#4]

Reports are the Greenby spam filter does not learn from your marking actions. 
I can't confirm or deny that.

Just a hint if you are using an email client ...

Login to www.greenby.com >>> email domain MANAGE >>> SETTINGS >>> Anti Span OFF
This leaves all email in the inbox for a POP3 / IMAP email program or app to collect.

Login to www.www.greenby.com with the same credentials as are used for the Pluenet Members Centre

[#5]

Yes, it doesn't seem to make any difference marking messages as not spam. That moves them to Inbox but subsequent messages still go to spam and this is still happening. Will try your latest suggestion and try to turn spam off. Thanks again.

[#6]

I'm in Settings on Greenby.com but can't see where to turn off Spam ("Anti Spam OFF"?). Unless it's to select Folders and then move the slider on the Spam folder to the left (off)?

[#7]

@Dalesman 

"Unless it's to select Folders and then move the slider on the Spam folder to the left (off)?"

No. Move slider to the Left - lower Level - is "More Aggressive". Move to the Right - higher Level - "Less Aggressive"

There is a separate slider/switch to turn Spam Filtering ON/OFF. All in Email/Settings

My previous experience suggests that marking posts in the Greenby Spam folder as Not Spam does teach the system to be more discriminating. But, as I subsequently reduced the Greenby spam filter from Level 3 to Level 8, I cannot now be definitive.

[#8]

Got it (I think). Anti Spam now set to off. Was looking in webmail settings before. Thanks again!