Help - Mail not sending - Saying incorrect password SMTP details correct

[ErniePatterson]

Hi - For the last week I have had a problem with my emails sending - receiving all fine, I have checked that the password for outgoing is correct with the correct SMTP settings and port. Mail just sits in the outbox. Then next day they disappear and it starts again - Even on webmail I can receive and then when i send it says "recipient's not known" for a valid email address that i was replying to. My mail box is still within quota - Any ideas would be appreciated or a number I can call in talktalk to discuss

[Gondola]

I don't recognise 'recipients not known' as a standard TalkTalk Mail error message so email sending that responds 'recipients not known' suggests that's a bounceback error from the recipient mail service. If so, what is the full error message including code(s). 

A simple failure to send via webmail may suggest the DNS lookup is failing for the email domain that you're sending to. i.e. TalkTalk's outgoing SMTP server looks up the DNS record for the domain you're sending to and for some reason cannot find that DNS record or cannot find a valid or active DNS MX server to send to.

If your SMTP password is being rejected then it's likely not the correct password for the sending email address. This is a different failure. So there are two issues that you're reporting here