There are a couple of places in the configure that it can add that extra line. Check the identities section and then check the Network section under sending. Something probably got updated and didn't ask.
That sending part has to be right. It amazes me that spamers can send all theirs with no problem but we can have one thing out of place and we are stuck with a error message.
You may also have to reopen the messages and redo the send part. I have had to delete the messages and re-enter them before it would send. It's kind of like when it is broke it just refuses to send even after you fix it. If there is one bad one, it will not send any until it is fixed/removed.
Hope that helps.
Later
