Are you attempting to send ONLY to BCC? There was a problem on that in a recent release. Are you using 91.9?

yes David you are correct. I have version 91.9.0 and also correct when I leave to TO: blank/empty this glitch occurs. If I enter my own addy, then it is ok and will send Bcc. I should not have to enter an address in the TO: to be able to send mail as this problem just recently began a few weeks ago and this is the only solution I have found to make sending Bcc possible. Even with only one address in Bcc it will still not send mail.

Well, this isn't a well-researched response, but I suggest reinstalling over your current installation, as I just tried and it worked fine. There seems to be a glitch somewhere.

Thank you for this suggestion, as I did a reinstall and the problem remains with sending error dialog box in the screenshot above returning as before when sending Bcc with the TO: box empty. Maybe a patch will be issued soon as I will have to use another mail program when sending only Bcc.

Well, this isn't a well-researched response, but I suggest reinstalling over your current installation, as I just tried and it worked fine. There seems to be a glitch somewhere.

There is a glitch where Yahoo do not allow BCC without a TO: beyond that what bugs are you aware of?