Verizon for the past week or two has been blocking all my outgoing e-mails from thunderbird. I receive: An error occurred while sending mail. The mail server responded: 5.7.1 The message you attempted to send was determined to be spam. Please visit http://www.verizon.net/spamfaq for more information.. Please check the message and try again. I just spent over an hour trying to talk with them. They blame thunderbird and say it is definitely not their server. They asked me to log in to their web mail application and try to send an e-mail from there. It worked, but I don't use that interface and I don't use that e-mail account. They say it is due to signature blocks. I don't have any defined. I've been sending this way for years. It just stopped. Is there any remote chance that thunderbird is actually doing the blocking? I don't believe so, but not sure how to convince verizon. :(