"A previoius support session with Thunderbird" - where and when was this? We don't offer interactive help, as far as I know. Was this a third party help outfit?

You have actually set two different problems.

If the sender has used Unicode or similar in his local part, then that's what he wants and the recipient can't meaningfully do anything about it. If you were change any character to another, it wouldn't be the same email address.

Within the message body, it's usually an inconsistency in the message formulation where it states one encoding (or none at all) but uses another. The appearance or rendering of such messages can usually be tweaked by changing the encoding used when viewing the message. In Thunderbird's menu, View|Character encoding.

I have just updated Thunderird and the address book no longer works with this same error message "There are non-ASCII characters in the local part of the recipient address" how can this be rectified please

Hi Site18, Try this: Go to Tools > Options > Advanced, and under the "General" tab, at bottom right, click on the Config Editor button. > Config Editor. After clicking on the "I'll be careful, I promise!" button, type in "mailnews.force" (without quotes) and you should see an entry for mailnews.force_charset_override. Make sure the Value is set to false (probably will be). If it's set to true, double-click on the line and the value will change to "false" (and the status will be changed to "user set").

Now right click on your Inbox and choose Properties. In the dialogue box that comes up, make sure that the checkbox “Apply encoding to all messages in the folder..." is NOT checked.

This solution was found at http://www.moorlandit.net/index.php/2010/07/thunderbird-character-encoding-139/. I updated the menu choices and navigation to reflect the newest versions.

Hope this helps, Norio

I am sorry this didn't work. Version of Thunderbird is 38.1.0 with windows 8.1 In fact both values were set as they should have been as you suggested. HELP please !!

sally.justice said

I am sorry this didn't work. Version of Thunderbird is 38.1.0 with windows 8.1 In fact both values were set as they should have been as you suggested. HELP please !!

Hello sally.justice, The original poster has marked this thread as being "Done" (solved), so it is not showing up in the "Needs Attention" section of the support forum.

So, if you want some help on your issue, you should go to https://support.mozilla.org/en-US/questions/new and follow the steps there to post your own question thread, because no one will be looking at this thread any longer.

Thanks, Norio

Those who have this issue since upgrading to Thunderbird 38 most likely hit the following issue:

https://bugzilla.mozilla.org/show_bug.cgi?id=1200050

In my case, it has helped to either remove a comma or an umlaut from the name part of the recipient.