Cannot send emails using Thunderbird (with a Yahoo email address) FIX !

Well, if like me you are using Thunderbird and Yahoo mail; you may well be having some issues sending emails out and getting the following two email errors:

1) An error occurred while sending mail. The mail server responded: Transaction failed: Cannot send message due to possible abuse; please visit http://postmaster.yahoo.com/abuse_smtp.html for more information. Please check the message and try again.

Followed by another error message ...

2) Sending of message failed. The message could not be sent because the connection to the SMTP server smtp.mail.yahoo.com was lost in the middle of the transaction. Try again or contact your administrator.

Cause: Unknown ! Something to do with Yahoo mail servers / Thunderbird itself? There is a lot of controversy around on the web about who is to actually blame for this.

Temporary fixes: until this is solved by either Thunderbird or Yahoo:

Go with which ever solution you feel most comfortable with.


1) The first change you can do is within Thunderbird go to Preferences > Advanced > General > and click on 'Config Editor'.

2) Find/Search for the setting "msgcompose.background_color". Set the value by double clicking on the value box from #FFFFF (white) ... to ... #FFFFFE (tiny bit darker than white).

Now I found that this worked; however if you still find yourself having problems there is one more setting you can change to send the mail successfully:

3) You can send the composed email as a Rich Text (HTML only) or a Plain Text only email. During the composition of a message (or forwarding of a message), select the 'Options > Format ... ' and then select either Plain or Rich Text. Try sending as HTML first to see if it sends. If not then you will need to send it as a plain text only email.

NOTE: If you are finding you have to send all your emails as 'Plain Text Only'; you can set Thunderbird up to send all emails (including those that you forward) as plain text.

To set this in Thunderbird open 'Tools > Options > Composition > General > Send Options > Set the drop down menu to 'Convert the message to plain text'. Click 'OK' on both windows and then restart Thunderbird to make sure the changes take effect straight away.

Any problems please comment. Hopefully this will be fixed soon.

Also ... a lot of people I found whilst researching this switched to a GMAIL account.

Resources used:

Yahoo Answers

and ...

MozillaZine Forums