In times of stricter data protection world-wide I think it shouldn’t be possible any longer to enter multiple recipients into the “To” and “Copy To” fields.
If such a restriction wouldn’t be applicable in general, then maybe a respective option could be added to settings.
There is an add-on that helps with this issue:
Thanks for this suggestion, but honestly I don’t know how somebody can “accidentally” send maills to multiple disclosed recipients.
My problem are senders putting my email address together with several others into a “to” or “copy” field. Since data protection has gotten rather strict in many parts of the world, I think Thunderbird (and other mail clients) should only accept one recipient in those fields.
I don’t know, but possibly there may be cases where it is wanted that all recipients see who else received the mail, like internal company mails or so. That’s why I’d plead for a default restriction plus a settings option to allow more than one recipient.
Such an implementation shouldn’t be major problem, I think, and last but not least Thunderbird could pioneer in setting a new standard where data protection is concerned.