Emails returned - Cannot send

[Keeping-up]

Once or twice a year I send an email to a group of about 24 people, and have had no problems in the past. Occasionally if someone had changed their address I would get a message back that it couldn't be delivered to them, but everybody else in the group still got the email OK 

Recently when I tried to send an email to the group, it was simply returned to me with a message saying it could not be sent. If I used Microsoft Mail it reported as a Windows error; if I used my Android phone it simply said it couldn't be sent. The result was the same whatever device I used: nobody got the mail and it was placed in my "Drafts" folder.

After much frustration I discovered that for two particular recipient's addresses, no email could be sent to them - and if it was a group email it was rejected entirely. Removing those 2 addresses from the "To" list allowed the email to be sent to the remaining members of the group with no problems.

Is this a new feature? Some form of anti-spam protection, perhaps, or what?

[Keeping-up]

Does nobody have any ideas?

[gg30340]

There are many reasons that could be causing the problem. 

Does the problem happen when using BTMail via webmail ( using a browser) rather than using an email client or app?

It may be that the email addresses that you removed have previously been used/spoofed to send spam and as such they are now blocked.

It could also be something as simple as a mis-spelt or a full stop in the wrong place in the email address.

It could be that the email addresses are no longer active.

It could be that the recipients have blocked your email address either accidentally or on purpose.

It could be that the recipients email provider has blocked your email address.

etc etc  

Have you been able to contact the email address holder and check if they are active and have you had them send you an email and has it been received. If it has been received what happens if you a) use the "Reply To" funtion and what happens if you start a new email with the address included in it.

[Keeping-up]

Thanks for the reply. It has prompted me to make a few more tests.

Yes it does behave in the same way if it is sent using webmail from a browser.

It would appear that if any one of the addresses in the list is incorrectly typed such as merely a full stop in the wrong place, or is no longer active, then ALL of the mails are rejected so that nobody gets it. This is surely a BIG change from the old situation where everyone except the incorrect addressee used to get the mail. It becomes a really major problem to resolve if - as in my recent case - there are two wrong addresses.