Usually, red font simply denotes that the email address is not in an address book. However, recently there has been a bug report on red font being reproduced when entering email address manually in TO field.

The good thing is that this is just a visual nuisance. It does not effect the email address nor effect anything to do with sending emails. So do not be worried.

However, if you have people in address books there is a simple way of selecting them using the 'Contacts Sidebar'. In a new Write message. Enable the 'Contacts Sidebar' 'View' > 'Select 'Contacts Sidebar' or toggle the view using f9 key. Select the address book select contact(s) click on 'Addto TO' button or other options.

Note that you can also drag and drop a name from the Contacts Sidebar into a TO field. You can select/highlight more than one contact by holding down 'Ctrl' key whilst using mouse to select, then click on one of the 'Addto To' buttons.

see image to assist.

Thank you very much.

As long as it doesn't otherwise interfere with creating and sending emails to those whose names/emaikl addresses appear in red, I'll live with it.