Since about 10 days, Thunderbird responds "Recipient address : missing authentification. Please check...". Using Thundrbrd since mny years. I've never seen that
I'm using Thunderbird since many years (more than 10). Though I changed nothing in my Thunderbird configuration, nor in my computer configuration, when I send any e-mail, Thunderbird produces an error message : " An error occurred while sending mail. The mail server responded: 5.7.1 <lal.andrian@club-internet.fr>: Recipient address rejected: Missing Authentication.
Please check the message recipient "lalatian@club-internet.fr" and try again."
This error message appears for all recipients I have tested. So, since about 2 weeks, I am able to receive e-mail in Thunderbird, but I can't send any e-mail. Thus, I must use other mail managers in order to send my e-mails. Best regards.
ప్రత్యుత్తరాలన్నీ (1)
This looks like club-internet.fr (or sfr) suddenly wants you to authenticate before sending a mail. Go to Tools -> Account Settings -> SMTP Accounts (in the left pane, last item in the list) and configure it to use the same account as for receiving messages and probably use Normal password as authentication method.