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Recently Unable to send (SMTP) from Thunderbird from Cox.com (now thru Yahoo).

Thunderbird Send and receive email
billb1111 replied
billb1111
billb1111

I have used Thunderbird for years with complete success. Recently (within the past month) I have lost the ability to send (SMTP) mail and receive the following error message: "Send Message Error, Sending of the message failed. Unable to authenticate to Outgoing server (SMTP). Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)." [I just change my from address to another one going through Network Solutions and the mail sends just fine.]

Everything seems to be in order when checking my settings. I finally called Yahoo and spent an hour on the phone with them, including a supervisor (in the background) and they were unable to correct the situation. Yes, since I had called them from their tech support line (I looked it up; did not call anything sent to me) and they worked on my computer trying to fix it. They finally said it was a Thunderbird issue and said I needed to contact Thunderbird.

I am able to send from my phone (Android) using the same cox.net e-mail address. My wife is able to send from her computer using her cox.net via Thunderbird. My wife's incoming mail is IMAP while mine are all POP.

I happen to have several cox.net accounts and get the same SMTP error on all. However, all receive POP mail just fine, but see the next paragraph.

[As an aside (?), I should note that after Yahoo attempted to "fix" the problem, ALL my incoming cox.net mail comes into ALL of my cox.net accounts regardless of which one is addressed.]

I don't even know where to start at this point. Thanks for any help.

Bill

I have used Thunderbird for years with complete success. Recently (within the past month) I have lost the ability to send (SMTP) mail and receive the following error message: "Send Message Error, Sending of the message failed. Unable to authenticate to Outgoing server (SMTP). Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)." [I just change my from address to another one going through Network Solutions and the mail sends just fine.] Everything seems to be in order when checking my settings. I finally called Yahoo and spent an hour on the phone with them, including a supervisor (in the background) and they were unable to correct the situation. Yes, since I had called them from their tech support line (I looked it up; did not call anything sent to me) and they worked on my computer trying to fix it. They finally said it was a Thunderbird issue and said I needed to contact Thunderbird. I am able to send from my phone (Android) using the same cox.net e-mail address. My wife is able to send from her computer using her cox.net via Thunderbird. My wife's incoming mail is IMAP while mine are all POP. I happen to have several cox.net accounts and get the same SMTP error on all. However, all receive POP mail just fine, but see the next paragraph. [As an aside (?), I should note that after Yahoo attempted to "fix" the problem, ALL my incoming cox.net mail comes into ALL of my cox.net accounts regardless of which one is addressed.] I don't even know where to start at this point. Thanks for any help. Bill

All Replies (3)

Wayne Mery
Wayne Mery
  • Rannpháirtí Barr-25
  • Stiúrthóir

Did it happen exactly on a version change? Coming from which version? (version history at Help > Troubleshooting Information > Show update history?

billb1111
billb1111 Úinéir na ceiste

It appears from my sent folder that the last message I sent successfully was on 6/28/2026 @ 5:22 pm. The closest update was Thunderbird 140.12.1esr (20260628021646) Installed On July 1, 20269 at 9:05:07 am.

I looked a little further into my mail history and found where I sent a message from a non-cox.net server on 06/29/2026 @ 11:219 pm including a note saying "I'm having a problem with my e-mail...saying mailbox unavailable so I'll send this through my church account." That would suggest the update is not the problem.

I do recall, about that period I received some sort of message from Yahoo wanting me to sign into my account which I believe I deleted/ignored and moved on. Looking in my trash folder, I see where I had some sign-in notifications from Yahoo where they had sent me a security code. Those were received 06/29/2026 at 4:10 pm, 10:09 pm, and 10:13 pm and addressed a general Yahoo account as well as the cox.net e-mail accounts.

Athraithe ag billb1111 ar

billb1111
billb1111 Úinéir na ceiste

Here is some additional information which may play in this problem.

I went into Thunderbird to settings and navigated to Passwords which are saved on my PC. For my two "primary" Cox accounts I seem to have multiple entries. Lets take just my one. It shows entries for mailbox://pop.mail.yahoo.com and a password changed in 2024; 2) oauth://login.yahoo.com (mail-w) and a password which appears machine generated changed 6/30/2026; and 3) oauth://login.yahoo.com (Mail-w ycal-w sdct-w) and a password which appears to be machine generated changed 8/7/2026. I believe #2 above is when the problem started and #3 is when I was on the phone with Yahoo and they were attempting to correct the problem remotely. I watched them working with sign-ins and those type passwords.

I don't now if that helps or not. Thanks.

Cuir ceist

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