I have seen one or two complaints about sending twice. Only on Windows and only on resume from sleep.

Is there anything that could be blocking network access to Thunderbird until it wakes up?

Open the error console (ctrl)Shift_J) and clear it. then try your send... what appears in the way of errors?

Thank you for the reply. I think there is something else going on however as this morning I began seeing other error messages. The errors occur in both Thunderbird and Mutt now. Two of the error messages are:

An error occurred while sending mail: The mail server sent an incorrect greeting: LA: 18010 - Service temporary unavailable, message deffered, try again later..

An error occurred while sending mail: The mail server sent an incorrect greeting: Too much load; please try again later..

I've contacted my hosting company, Siteground, but their usual response to problems seems to be that the user's email client is incorrectly configured. Strange because I have not changed any settings in Thunderbird or my ~/.muttrc file.

I've got the same problem and it has nothing to do with sleep. I suspect this version has had the time out delay shortened because its only Thunderbird that does it.

I recall the time out setting was part of the interface at one time. My mail server uses security measures to make sure the IP address of outbound mail is arriving from one of our addresses.

I don't think changing to an earlier version is a good idea but changing to a different mail client might.

When Mutt started acting up I checked with my hosting company and they acknowledged that they did have a problem with the mail server, however that problem has been resolved. Indeed Mutt is not having trouble anymore, but the problem with Thunderbird remains. Thus, I think Technoaussie is correct.

My solution has been to migrate to Evolution. (Mutt is great for sending mail from a script, but not my idea of an email good time.)

I have been having a lot of problems with Thunderbird in the last three days. 1. Wont scan outgoing emails because of security settings. So tried to alter settings with AVG without success. 2. I spent two hours yesterday with Virgin Media's technology people trying to work out why my desktop computer clock was out of sync without understanding why. 3. VM's technicians got it working late yesterday but on restart to day got the timed out message immediately I hit 'send'. I have uninstalled TB and re-installed it twice. Virgin assures me that the email servers for imap and pop3 are all OK. Just tried to download Windows Live Mail but there appears to be a problem there as well. However, my web mail is working so not cut off completely. I may dump Thunderbird and pay for a different email client now.