Is this a new development, say after an upgrade of Thunderbird? What version of Tbird are you using? Are these addresses stored in any address books?

Thanks!

60.3.1 32 bit

It is a new development but I can not tie it to an update . Didn't notice the problem until 3 weeks ago DIdn't notice an upgrade

Addreses are stored yes. Regularly emailed. If I switch the order it still happens to the first email address. .com becomes .co

If you are using version 60.3.1 then it is an old version and probably not related to any update. Is there any reason why you are still using an old version of Thunderbird ? Is it because you want to use an old version in order to use old addons that do not work on newer versions of Thunderbird? In which case you could try updating to a version that should still work with addons and then select option not to update.

If it is a bug then developers will not be trying to fix bugs on old versions.

It is normal to use one line per email address which should work and allow you to send one email to 20 people.

You could use the 'Contacts Sidebar' to select all the contacts (depress 'Ctrl' key whilst selecting) and then click on one of the buttons such as 'Add to To'. You enable Contacts Sidebar via 'View' and select 'Contacts Sidebar'. This would then add all contacts in one go putting each one on a new line. This also makes it easy to remove one if added accidentally. See image attched below.

If you regulary send to those same people, you could set create a mailing list and use that instead.

• how-create-and-use-mailing-lists-thunderbird

Forum is currently being messed about with devs trying to come up with a solution to spammers so posting links has become a problem. If you want to update to the last version that is compatible with most addons then I'll need to send you a message via Sumo Messaging, so let me know if it is required.