Authentication required.

User Help for Mozilla Thunderbird
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Joined: August 26th, 2005, 10:05 pm

Post Posted October 30th, 2019, 6:33 am

I have been using TB for years. Now when I send it rejects saying authentication required. The error code is 550 5 .1.0. Can anyone help me. Also I am semi computer literate.


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Joined: July 30th, 2003, 5:06 pm

Post Posted October 30th, 2019, 8:07 am

See if the problem occurs when you send a message to somebody who using a different email provider, such as gmail. The problem might have nothing to do with your copy of Thunderbird, it could be the address you're sending to no longer works.

If you're still unsure if Thunderbird is to blame, try sending a message to the same recipient using webmail (browser based) and see if it has the same problem.


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Post Posted October 30th, 2019, 1:42 pm

Authentication means sending a username and password to prove you were entitled to use the mail server.

The outgoing server you must connect with is called an SMTP server (it uses the Simple Mail Transfer Protocal, hence SMTP).

Are you sending via an SMTP mail server provided by your internet provider? Many of these used to be configured that as long as you were connected via their service (i.e. not connecting via some OTHER internet service when not at home) then no authentication is necessary because they figured if you were connected via their internet service, you must have an account. With increasing security concerns many such services now require authentication to send mail even when connected to their internet service.

If your server didn't require authentication before but does now you'll need to enter a username and a password. Username is typically your email address (some want your full address, others only want the part before the @, some very rare ones may even want an account number). The password is whatever has been set up with the service as your password -- TBird won't know until you tell it.

I'd suggest logging into your ISP's web site and do a search for parameters for setting up email. Such a page should give you the information they require.

See this Knowledge Base article re setting up SMTP servers: ... hunderbird
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