Some e-mails I am sending out of Tbird are not arriving at their destination. I noticed this last week. I have been using Tbird for many years, have not changed anything. I don't get any kind of rejection message. Other messages I send arrive fine. Test messages to myself arrive. But I have -- for example -- been unable to post from Tbird to my listserv. I have sent control e-mails out of my provider's webmail (rcn.com) and they arrive, but comparable e-mails from Tbird do not. RCN says they think the problem is in Tbird. Account settings are sending (as always) to RCN's smtp address.