you go into account settings. Right click the account in the folder pane and select settings in the outgoing server (SMTP) entry you select you outgoing server and edit it.

Still not working but I am pretty much dumb when it comes to computers (sorry) . I think I went where you told me & edited to my e-mail address & default but didn't seem to change any thing . does it sound like I'm doing it right ?.

Open Account Settings

You need to go down the list of accounts and look at the last one, It's called "Outgoing Server (SMTP)".

Selecting that will show a list of the smtp server settings. Pick the one that's not working and click the Edit button.

Then you can change the "Authentication method". You probably need the one that mentions password or maybe normal password.

DON'T change anything else - your settings may not agree with my example picture but that's not important; what's right for the particular account shown in my picture isn't necessarily correct for any other account. We're just trying to switch away from "Encrypted password" here.

Thanks for all your help, now I will be able to sleep tonight . Hope you all have a Merry Christmas & a happy new year.

I have the same problem. At what TB version was not supporting encrypted passwords implemented? Why are you trying to switch away from encrypted passwords?? Isn't this a high security issue? I installed TB 45.5.1 on Dec. 7th but the issue didn't show up until Dec. 16th. I sent e-mails from Dec. 7th to Dec. 15th without encountering this issue. How come? I feel like I have been blind sided with this. Regards. My environment: desktop PC with i7 cpu, Win7 Pro + updates.

AvidResearcher said

I have the same problem. At what TB version was not supporting encrypted passwords implemented? Why are you trying to switch away from encrypted passwords?? Isn't this a high security issue? I installed TB 45.5.1 on Dec. 7th but the issue didn't show up until Dec. 16th. I sent e-mails from Dec. 7th to Dec. 15th without encountering this issue. How come? I feel like I have been blind sided with this. Regards. My environment: desktop PC with i7 cpu, Win7 Pro + updates.

Blind sided by what? The type of password that a server will accept is decided by that server owner, not Thunderbird. Likewise the use of encrypted connections is also a function of the server. Thunderbird supports the encryption, but if the server it is communication with does not then failure to communicate will occur.

Hi Matt; I was blind sided by suddenly being unable to send an e-mail with encryption after many moons of not having this issue. Before creating my post I had contacted my ISP (Cox) support. We verified that my settings were correct (and unchanged) and did a test send which failed. We did another test using their Web mail capability (a different path) and was successful. It appeared to point to TB as the source of the issue. With your information that the server is responsible for encryption I am pointed back to my ISP which I will pursue and let you know. I am very vigilante about my digital security and privacy. Hence, my post. Regards, Rodg

Comprehensive, and apparently recently updated (September) website here.

Next step would be to ask you to post the settings from Thunderbird.

Please add the troubleshooting information to your post. To find the Troubleshooting information:

• Open Help (or click on three-line-icon and select Help);
• Choose Troubleshooting Information;
• Clear the check box "Include account names";
• Use the button Copy to clipboard to select all;
• Paste this in your post.

SMTP Server settings: Server Name: smtp.cox.net Port: 465 Connection security: SSL/TLS Authentication method: Encrypted password User Name: my user name

Troubleshooting information:

 Application Basics

   Name: Thunderbird
   Version: 45.5.1
   User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1
   Profile Folder: Show Folder

             (Local drive)
   Application Build ID: 20161130024037
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Memory Use: about:memory

 Mail and News Accounts
   account1:
     INCOMING: account1, , (pop3) pop.cox.net:995, SSL, passwordCleartext
     OUTGOING: , smtp.cox.net:465, SSL, passwordEncrypted, true

   account2:
     INCOMING: account2, , (none) Local Folders, plain, passwordCleartext

   account3:
     INCOMING: account3, , (pop3) pop.cox.net:995, SSL, passwordCleartext
     OUTGOING: , smtp.cox.net:465, SSL, passwordEncrypted, true

   account4:
     INCOMING: account4, , (pop3) pop.cox.net:995, SSL, passwordCleartext
     OUTGOING: , smtp.cox.net:465, SSL, passwordEncrypted, true

   account5:
     INCOMING: account5, , (pop3) pop.cox.net:995, SSL, passwordCleartext
     OUTGOING: , smtp.cox.net:465, SSL, passwordEncrypted, true

   account8:
     INCOMING: account8, , (pop3) pop.cox.net:995, SSL, passwordCleartext
     OUTGOING: , smtp.cox.net:465, SSL, passwordEncrypted, true

 Crash Reports

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   Lightning, 4.7.5.1, true, {e2fda1a4-762b-4020-b5ad-a41df1933103}

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max chars. exceeded so removed last printer info.

The cox website does not ask you to set for encrypted password. Set it to "normal password" . You don't need to specifically encrypt the password because the entire transaction with the server is encrypted courtesy of the connection being made using SSL.

If you have manually set this to "encrypted password" then it is a problem of your own making.

Note that your incoming mail uses the regular password setting, not "encrypted password", and also uses SSL.

HI Zenos; Thanks for the response. True. Cox does not ask for an encrypted password. Yes, I can and will set the option to 'normal password' now that I know that the encryption is taking place via SSL. Take note: I have had the authentication method set to "Encrypted Password" since I can't remember when because it has been so long (years). Something changed and the highest probability is either in TB or Cox is the source. I have talked to Cox tier 2 support and they are denying it is on their part. They also said that they have had "a lot" of calls on this topic with TB. Regards, Rodg.

They got lots of calls, and we got one. Funny in a sad way.

Hi Matt; Amen to that! Have a wonderful holiday season. Rodg.