User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.6) Gecko/20060728 Firefox/1.5.0.6 Build Identifier: thunderbird version 1.5.0.5 (20060719) Thunderbird should warn the user if there is more than one recipient in the to:-field. So the user can choose whether all the recipients are moved to the bcc: field or stay in the to: field. This would reduce emails in which you can find the whole addressbook of another person. In most cases people don't want all the recipient to see all emailaddresses. I was thinking about this feature, after I got a (funny) email that was forwarded several times, and everybody put the whole addressbook to the to: field. So when the email finally reached me, there where more than 2000 emailaddresses in the body of the email. So help making the internet a saver place and add this feature. It help protecting the own privacy and the privacy of others. (this is probably poor english, so maybe someone can "translate" it) Reproducible: Always Steps to Reproduce: it's a missing feature, what should I write here :-)