My onlu suggestion would be to either disable Norton or see if there is an option in Norton to bypass email clients.

re Norton

Exit Thunderbird Access Norton Firewall set thunderbird as allowed program see image.

It's in "allow" mode which is why I can receieve and send new e-mails. Problem is with the "reply" and "forward" functions of Thunderbird. Thanks anyway....

OK....think I have a clue on what may be happening. This is only happening to my MAIN e-mail that I use 90% of the time. I have 2 more Comcast emails through Thunderbird that do no have this problem. My thought is that the Thunderbird file that has my log-in info for my main account might be corrupted and needs a refresh. Is there a proper way to "refresh" that e-mail info without loosing all the stored information and emails ?

Turning off Norton made no difference.

Vlad

Do you only have one email address / mail account ?

Does that one mail account have more than one identity? In Account Settings - Select name of account bottom right - click on 'Manage Identities' button Is there only one identity listed ?

Do you use a Pop or Imap mail account ?

When you click on 'Reply': Is the 'To' field of received email put into the 'From' field of email you are composing and does that 'From' field contain the mail account email address or another identity of that account?

In Account Settings In left pane, Select name of account Bottom right - 'Reply from this identity when delivery headers match...' Have you entered anything into that location?

re : I have 2 more Comcast emails through Thunderbird that do no have this problem.

Do you have the three comcast mail accounts set up as separate mail accounts and all three mail accounts display as separate accounts in the Folder Pane using their own set of folders ?

Check each account is using it's own smtp server. I'm thinking the Reply/forward is being perceived by server as a relay using an smtp set up for another email address.

In Account Settings Left Pane - Scroll to bottom and click on 'Outgoing Server (SMTP)' You should see a list of three outgoing smtp servers - one for each email address.

Select first in list and click on 'Edit' Description : type the email address which is the same as the 'User Name' Click on 'OK'

Repeat the above action for each smtp server in list. Obviously the user name = email address will be different for each smtp. If you do not have one for each email address: click on 'Add' and create one for account/email address that does not have it's own smtp. Entering DEscription = email address which is same as User name email address.

Then check all accounts are using their own smtp.

In Left Pane: select account name and look bottom right for Outgoing Server (SMTP) This is where the description you entered helps - you should see the same email address as the acount you selected. If this is not correct - clickon the drop down option and select the correct email address for the account. DO NOT click on 'Edit SMTP-Server' button because you only ever do that when you already know it is using the correct server. It is very rare you ever need to update an smtp server, but it is more common that a wrong smtp server is being used.

I have 3 Comcast e-mails ...all different names....all set up the same exact way. They have all worked perfectly for the past 6 years and I have changed nothing on them Each e-mail account has only 1 identity. I'm not sure about POP or IMAP..... don't know where this is configured. My bet is that if I was asked 6 years ago I would have chosen POP. All the emails I download from Comcast to Thunderbird are kept on Comcast servers also. When I click on Reply.....the "to " and "from" show the correct email names There is nothing in the "Reply from this identity when delivery headers match.." section. It's empty.

Thanks, Vlad

You are right...it was an smtp issue. Unfortunately the 2 emails were sharing the same name "comcast - smtp.comcast.net (default). Unfortunately too......I acted too fast and edited all 3 of them and gave them new names ( name 1, name 2,name3) so that I could associate each with a specific email. This fixed finally my main email that was giving me problems....but at the same time messed up the other 2 emails. I also deleted the passwords for those 2 because they were not working and giving me the same issue.. So ...question : is there any way to add passwords to an existing account that doesn't have one.

Sorry but I messed up this out of my own ignorance as to what to do.....

I shut down Thunderbird and restarted......it asked me for the new passwords and now everything is back to normal !!!! Thanks a million for the Help. Vlad