Some emails are bouncing back

I get some emails through but not others. If I send test emails to myself, sometimes they come through after an hour or so and sometimes it says it's undeliverable. Friends emails sometimes come through, sometimes they don't. So I have no idea what emails I've not received. 

davef28​ "I have had letters from British Gas and TV Licensing to say that emails they are sending are bouncing back undeliverable"

This is an issue that regularly comes up on this forum. In the past it as been emails from  local authorities, travel companies, onlne shopping sites, travel companies  and many others that have failed to arrive in VM mailboxes. 

VM run a number of checks on all incoming email over and above simply checking the contents of an email to see if it looks like spam.

Many organisations and companies use automated email software to manage:

• transactional emails such as sending OTP's  and PIN's  as well as confirmations of purchase
• sending out regular newsletters or marketing to mailing lists.

Putting it simply, it seems that the settings of such automated systems often cause VM to reject those emails because VM cannot be certain that they have been sent on behalf of the organisation or company themselves.  It may well be down to a recent change that BG and TV Licensing have made to their automated outgoing email setup.

"Some BG emails do get through as do many others." that's probably because those emails are being sent manually by BG rather than being sent by their automated system so they pass VM's strict checks.  Again that's a regular occurrence in these cases

The only way to know precisely why some emails are not getting through is to get sight of the error messages or non delivery emails that the sending organisation receives from VM each time they send you an email.   

Those, along with information from BG's and TV Licensing's email logs will give the reason VM have blocked the email but getting that information from the customer support staff of sending organisations is difficult at best and in most cases it's impossible.

There really isn't anything you can do to ensure these emails come through, other than switching over to using a non VM email account as your contact address for these companies. 

Sorry I cannot be more helpful,

Coenoby