Very odd 'failure to send' message

[Stiggywig]

Using Thunderbird I sent a message I am (aaaaaaa) to half a dozen people that brought the response 

"Sending of the message failed.

An error occurred while sending mail. The mail server responded:  

<aaaaaaa@talktalk.net>: Sender address rejected: not owned by user 3@10111010.

 Please check the message recipient "bbbbbbb@dsl.pipex.com" and try again."

I then tried further recipients individually all frequently mailed and got the same response.

The error message makes no sense to me whatsoever - anyone seen this before?

[Thabile-TT]

Hi there @Stiggywig I'm sorry about the email issue you are experiencing I will need to look into your account to further assist you. 

[Stiggywig]

Sadly the problem has returned only this time I can send Mails and my wife can't.  ???

[Philile-TT]

@Stiggywig that is great, thank you for the update. 

[Stiggywig]

No action required - checked and service looks to be resumed to normal - Thanks

[Philile-TT]

@Stiggywig please advise if you still require assistance

[fr8ys]

Ok, as you can't send via Webmail, you will either have to phone or chat, or wait for the support team to return Monday.

[Stiggywig]

Steve - thanks, I tried webmail from my phone - same result, so not Thunderbird. I should have thought of that test

[Philile-TT]

@fr8ys thank you for the support. 

[fr8ys]

Can you try using recommended settings for TalkTalk emails and derivatives such as yours please 

https://help-centre.talktalk.co.uk/Email/Set_up_TalkTalk_email/Email_settings_to_access_TalkTalk_ema...

Can you send via Webmail?