Sending of the message failed.

Question

Sending of the message failed.

Richmond TWp Road Dept 0

Using Thunderbird and receiving the following: Unable to authenticate to Outgoing server (SMTP) smtp-mail.outlook.com. Please check the password and verify the ‘Authentication method’ in ‘Account Settings | Outgoing server (SMTP)’.

I have followed all the suggestions but cannot get it working. I can receive.

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4 answers

Your answer

Answer 1

Kai-H 30,315 Microsoft External Staff Moderator

Hi, Richmond TWp Road Dept

Your screenshots show that OAuth2 and port 587 are set up correctly, and Thunderbird already has permission to send. So the problem is likely an old saved sign-in, or SMTP being blocked on Microsoft's side for this mailbox.

Here are some suggestions you can try:

Check the exact error first. Try to send an email. When it fails, press Ctrl + Shift + J in Thunderbird to open the Error Console. If you see"535 Authentication unsuccessful, SmtpClientAuthentication is disabled for the Mailbox", the block is on Microsoft's side and no Thunderbird setting will fix it. This happens a lot with newly created Outlook.com/Hotmail accounts. It sometimes starts working on its own after a few days. If it doesn't, contact Outlook support and ask them to enable SMTP AUTH for your mailbox.

Clear the old sign-in. Your screenshot lists Thunderbird twice, which suggests an old sign-in may still be saved.

Go to https://account.live.com/consent/Manage, select Thunderbird and choose Remove these permissions.

In Thunderbird, open ≡ > Settings > Privacy & Security > Saved Passwords. Remove every entry starting with oauth:// for your Outlook address.

Under Cookies, make sure Thunderbird accepts cookies from websites.

Close Thunderbird completely, reopen it and send a test email. Sign in again when Microsoft asks.

Check the user name and webmail. In Outgoing Server (SMTP) > Edit, the User Name box should contain your full email address. Also send one test email from outlook.com in your browser. If it asks you to verify your account, finish that step, because unverified accounts can't send from mail apps.

Let me know what the Error Console shows and we can go from there.

Richmond TWp Road Dept 0 Reputation points

2026-11-03T01:26:57.6433333+00:00
GenericSendMessage FAILED: Sending FAILED! Unable to authenticate to Outgoing server (SMTP) smtp-mail.outlook.com. Please check the password and verify the �Authentication method� in �Account Settings | Outgoing server (SMTP)�. NS_ERROR_FAILURE: Sending FAILED! Unable to authenticate to Outgoing server (SMTP) smtp-mail.outlook.com. Please check the password and verify the �Authentication method� in �Account Settings | Outgoing server (SMTP)�.

onSendStop resource:///modules/MessageSend.sys.mjs:1720

MsgComposeCommands.js:6583:13
Richmond TWp Road Dept 0 Reputation points

2026-11-03T01:29:14.6933333+00:00

So far I have tried this email on 3 different computers all with the same result. NOTE: in web browser I can send messages. It is only in Thunderbird I have the problem. I do have other Hotmail, & Outlook address on this computer using Thunderbird that function with no issues.
Kai-H 30,315 Reputation points Microsoft External Staff Moderator

2026-11-03T08:54:02.0166667+00:00

Hi, Richmond TWp Road Dept

Thanks for the details. The fact that this happens on 3 different computers while your other Hotmail/Outlook accounts work in the same Thunderbird points to something specific to this one account. Could you check these:

Authentication method. Go to Account Settings > Outgoing Server (SMTP), select the entry for this address and click Edit. Make sure it's set to:

Server: smtp-mail.outlook.com

Port: 587

Connection security: STARTTLS

Authentication method: OAuth2 (not "Normal password", which Microsoft no longer accepts)

User Name: the full email address of this account

Wrong SMTP entry assigned. With several Outlook accounts in Thunderbird, it's common for this account to end up using another account's SMTP entry. In Account Settings, select this account and check the "Outgoing Server (SMTP)" dropdown at the bottom. It should point to the entry with this account's username.

Alias vs. primary address. If this address is a secondary alias on another Microsoft account, OAuth sign-in has to use the primary address. You can check this under account.microsoft.com > Your info > Account info > Edit account info.

Reset the saved token. Go to Settings > Privacy & Security > Saved Passwords, delete the entries for this address (smtp-mail.outlook.com and oauth://login.microsoftonline.com), restart Thunderbird and send a test message. Sign in again when the Microsoft window pops up.

Revoke and re-consent. At account.microsoft.com > Privacy > Apps and services, remove Thunderbird's access and then sign in again from Thunderbird.

If it still fails after all of this, let us know which authentication method is currently selected for that SMTP entry.
Kai-H 30,315 Reputation points Microsoft External Staff Moderator

2026-11-04T09:08:11.2433333+00:00

Hi, Richmond TWp Road Dept

Is there any update from you?

If yes, please feel free to let me know.

Answer 2

Richmond TWp Road Dept 0

Screen shot of my permissions using web browser:

User's image

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Answer 3

Richmond TWp Road Dept 0

User's image

Here is a screen shot

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Answer 4

Richmond TWp Road Dept 0

So far most answers are centered on the O{ath2 requirement. I have done that, have port 587 ,etc ,etc, etc. Would be really nice if MS actually built systems that worked or fixed items when they are not functioning. Having email address that cannot send is entirely useless. Sending of the message failed.

Unable to authenticate to Outgoing server (SMTP) smtp-mail.outlook.com. Please check the password and verify the ‘Authentication method’ in ‘Account Settings | Outgoing server (SMTP)’.

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