can't send E-Mails

This is not Thunderbird rejecting you. It is the server. '''sender rejected. ''' means the server rejected you for some reason. Email address in the 'From' may not be the expected one. Perhaps a typo? Username may have a typo error. Server settings may not be correct - or server is being a pain ! Maybe you have enabled a VPN and the server cannot see your IP address, so it's rejected you. Switch off VPN. It can also reject you if your email address or IP address are on a server blacklist. Or perhaps you failed the Server Spam filter. Usually a bit more info is in the error to help identify the issue. But we need to rule out the obvious ones first. As a heads up the Spectrum servers have been having problems and some workarounds have been required. But first let's just be really sure regarding the data being used. Advise you check your current Outgoing SMTP settings as well. Check the email address because if it's the same as the one you posted then it will fail. There is supposed to be a period/dot between charter and net. You need to check the SMTP outgoing server settings. In Account Settings '''Left '''pane - scroll to bottom just below 'Local Folders' is 'Outgoing Server (SMTP)' - click on it. All smtp outgoing server will be listed. Select the one which has 'Username' = charter email address. click on 'Edit' * In 'Description' : type the email address - this will become useful later. According to the website you should be using the following for the Outgoing SMTP server. * Server name: '''mobile.charter.net''' * Port: '''587''' * User name: '''full email address''' - check for typos * Authentication Method: '''Normal Password''' * Connection Security: '''STARTTLS''' Then click on 'OK' check the account is really using that outgoing SMTP server. * In Left Pane * Select the name of the account In default identity * Email address - please be very careful and check for a typo. * Bottom right - Click on 'Manage Identities' * Check to see if there is more than one identity listed * If yes, select and check there are no typos. * Edit if required and click on 'Close' * Near the 'Manage Identities button - locate the 'Outgoing Server (SMTP)' Do you see the information you typed in the Description field? If yes, that is good - leave alone. If not, then wrong one is selected '''DO NOT '''click on 'Edit SMTP_Server ' button * Click on the V drop down to see the drop down list and select the one which has the correct description. Check your 'Address Books' Use the 'All Address Books' option Make sure you are using the column format Enable the 'Address Book' column header Sort by 'email address' column header look for your email address It might list more than one Check the spelling in all of them. Finally, exit Thunderbird and allow a few moments for background processes to complete. Start Thunderbird. When posting data, please do not type it as you might unwittingly post a typo. If you get an error message then get a screenshot and upload the image to this forum. To post data on what server settings you are using: you can post image(s) what you see in Account Settings you can also use 'Help > Troubleshooting Information' scroll down to 'Mail and News Accounts' section and post an image of what it shows. Report back with images showing all the current settings and confirm - you really do have a correct email address in all the locations I mentioned.