re :The mail server responded: 5.1.0 Authentication required.

You need to check the settings for your outgoing server. This could mean username is incorrect eg: it should be full email address. Authentication method: 'Normal Password' unless you are using OAuth2. Connection Security and Port also need to be correct for the server name requirements.

Help > Troubleshooting Information Copy and paste the information you see under 'Mail and News Accounts.' into this forum question and we can check for something that is amiss.

Thank You Toad-Hall!! I don't know how the settings got off but that is exactly what it was. Thanks Again!! There is one other thing that I haven't been able to find an answer to. I recently changed internet providers, I changed from cable to fiber. My email address is through my old cable account, (it is a comcast.net address). If I was to change my address to the new fiber account, (becoming a adams.net address), while keeping Thunderbird. What would happen to emails that are presently in my inbox? Nobody seems to be able to tell me this. Any help would be deeply appreciated!! Thank You!!

re :old cable account, (it is a comcast.net address) If you set this account up as a POP mail account, then all emails should be downloaded and stored on your computer. You could create some relevant folders in 'Local Folders' mail account and move batches of emails from the pop account folders into the 'Local Folders' mail account. Then remove the old pop account via Account Settings > Account Actions. This would give you continued access to emails whilst cleaning up the active accounts.

If you had an IMAP mail account, you might have downloaded full copies before you left them. You can verify you have mbox files by accessing your profile name folder. (some info below in manual section on how to check for mbox files) If you have mbox files of good size, you can either use an addon extension called ImportExportTools NG to import the mbox files from imap account into Local Folders OR manually move files to 'Local Folders' mail account, but suggest you do this with Thunderbird closed.

Using an addon - ImportExportTools NG

• https://addons.thunderbird.net/en-US/thunderbird/addon/importexporttools-ng/

How to install addon:

• https://support.mozilla.org/en-US/kb/installing-addon-thunderbird

How to locate profile name folder to check for Imap mbox files and manually move those files. In Thunderbird

• Help > Troubleshooting Information
• Click on 'Open Folder' button

A new window opens showing you the contents of your 'profile name' folder.

• Exit Thunderbird now.

• Click on ImapMail' folder to see contents.
• Click on the imap mail account name folder to see contents.

All fully downloaded emails are stored in mbox files. The mbox files do not have any extension. If they have a good size, they contain emails. All .msf files are just indexing files and do not have any emails. Any .sbd folders mean you had subfolders and they may contain mbox files.

• Copy and paste mbox files from the imap account into 'Local Folders' mail which in in the 'profile name' folder > 'Mail' folder.

I have included an image below as a guide, an example of copy and paste an imap Inbox mbox file into 'Local Folders'. I would suggest, if you copy and paste files with a name like 'Inbox', that you then rename the file to eg: OldComInbox.

• Once all mbox files are copied over, start Thunderbird.

Check you can see those folders in 'Local Folders' - you can rearrange and sort them as required.

If you have a new email address supplied by adams then you can add that email address as a new existing mail account. Menu icon > New > Existing Mail account

Do not alter any account settings to do with the old comcast account. Once you have got copies of emails into Local Folders mail account, then you can remove the old comcast account.

What if adams.net say you can keep the 'comcast' email address and you just need to point the Account Settings to a new adams server ?

Whilst adams may say you can keep comcast email address, you will not be using comcast server, so if you currently have an imap comcast account then all emails are stored on the comcast server, if you changed server settings to point to an empty adams server, then all emails in the imap account will be lost. Imap accounts only show what is on server.

This is why it is important to get copies of emails out of the imap comcast account and into Local Folders first.

Once you have got good copies in 'Local Folders' account then you change the comcast email address to point to a new adams server.

I have done everything spoken here and still get error 5.1.0 WHY the hell can't we speak to someone and trouble shoot this like the 2 hours I spent with Comcast, to only determine this was a Thunderbird issue.

drhsecurity re :WHY the hell can't we speak to someone and trouble shoot this like the 2 hours I spent with Comcast,

Just in case you have forgotten, you are using a Free software program and Free access to help provided by other Thunderbird users offering their Free time in a voluntary capacity. The are no offices nor telephones and those who help are all over the world.

If you are getting exactly the same error message : "The mail server responded: 5.1.0 Authentication required. " Then it is likely you have not got your settings correct.

When you post a response to someone elses question, you are asking only that person for help. They may not be able to help. I only got an email because I had forgotten to stop following a question that is already marked as 'solved'.

Please start your own question and provide some details,eg: The full error message and info located: Help > Troubleshooting Information Copy and paste the information you see under 'Mail and News Accounts.' into that new forum question.

Sorry to have ruffle feathers here. I have been using thunderbird without issues for over 20 years. Suddenly sending email on 1 account, from my desktop only, not iphone or ipad gives me an error 5.1.0 server authentication error. Comcast could not remediate, so I have turned to this forum. I am a total tech dummy

Toad Hall, I'm sorry that it took so long for me to get back to you! The first on of the three options that you sent to me solved my problem. Thank You Very Much! Jim F.

drhsecurity When a question for another person is solved - marked with a 'Chosen Solution' then you need to check whether the chosen solution fixes your issue. If it does not then you need to create your own question and provide the information already mentioned. It is not considered helpful to keep sending emails to that person who created the original question, which is what you are currently doing.

I'm not able to mind read nor know what outgoing server smtp settings you are currently using. Provide that information when you create a new question for your particular issue, so we do not keep sending Jim.F a load of emails he does not want nor need.

Toad-Hall said

re :The mail server responded: 5.1.0 Authentication required. You need to check the settings for your outgoing server. This could mean username is incorrect eg: it should be full email address. Authentication method: 'Normal Password' unless you are using OAuth2. Connection Security and Port also need to be correct for the server name requirements. Help > Troubleshooting Information Copy and paste the information you see under 'Mail and News Accounts.' into this forum question and we can check for something that is amiss.

An error occurred while sending mail. The mail server responded: Authentication required. Please verify that your email address is correct in your account settings and try again. checked all above but still get the error message.Outgoing Email has been working for for years until this week

An error occurred while sending mail. The mail server responded: Authentication required. Please verify that your email address is correct in your account settings and try again. checked all above but still get the error message.Outgoing Email has been working for for years until this week

To simlom and anyone else who reads this who is new to this question: If the 'Chosen Solution' and further comments is not helping you....

Please start your own new forum question because the person who created this initial question does not need to be bombarded with emails from people discussing their issues.

In your new forum question, please provide the following information to help your case. 'Help' > 'Troubleshooting Information' Copy and paste the information you see under 'Mail and News Accounts.' into this forum question. Supplying this info is important.