I have Enigmail/Thunderbird set up to automatically encrypt email when I send it to a particular recipient. I have it choosing my keys "By Per-Recipient Rules" and "By Email Addresses according to the key manager". I've edited the rules, and have a single rule for my wife with "Encryption" set to "Always".
Thus, when I email my wife, it automatically encypts. When I email anyone else, it doesn't. However, when there are multiple recipients, and one of those is my wife, I get a dialogue window asking me to make a choice. Is there a way to automatically not encrypt such emails? That is, automatically encrypt when my wife is the sole recipient, otherwise, don't (supressing a dialogue window).