Text colour change

When typing an email address in the To: box, why does the address sometimes turn red and become barely visible on the white background. If I delete the part before the @ sign it goes black. This colour change is so frustrating because it is difficult to see what is being typed and seems unnecessary, why does it not stay black?

Perhaps you are using version 60?

From the v60 release notes - a good reference to check when you update - “During address entry, the matching part of the address is now shown in bold. Preference mail.autoComplete.commentColumn allows to display the address book where the address is stored.”

The red means what you typed does not match any of your contacts. I agree it is a bit too light. I do not know of any way to change it. We will need to wait for a fix