From MozillaZine Knowledge Base
This article provided instructions for email providers that users frequently asked for help on. Due to the remote database used by the new account wizard in Thunderbird 3 its no longer being updated."
Thunderbird supports using POP and IMAP mail servers for fetching/reading new messages, and SMTP servers for sending messages. It does not support webmail. If you want to use webmail (or WebDAV or HTTPMail) with Thunderbird you need to use an add-on that essentially makes it emulate a POP or IMAP account.
Your email provider (frequently it's your ISP) creates an account (that you can also access via webmail), gives you permission to access their mail servers, assigns you a email address, username, password etc. Thunderbird doesn't do that, it's just an email client (like Outlook Express, Eudora, etc.) The account you create in Thunderbird is basically just a way to tell Thunderbird how to access your email providers account/mail servers.
This tutorial explains how to create a account in Thunderbird, but it doesn't have any of the information you need to configure it (such as your email address, username, password, mail server etc.). If your email provider isn't listed and the support page on their web site doesn't have instructions for Thunderbird, it's easiest to follow instructions for Netscape or Mozilla as the main difference is the menu command used to display the account settings window.
Thunderbird doesn't leave a copy on the POP server when it downloads a new message. Check "Tools -> Account Settings -> Server Settings -> Leave messages on server" if you want to be able to access your mail using either Thunderbird or a browser. You may want to set the number of days it keeps a copy to avoid filling up your webmail mailbox.
A few providers may state that you need to make a connection using SSL, while actually requiring TLS.
The two protocols are related but they are not interchangeable - you need to specify the correct protocol. If you can't make a connection using SSL, try either TLS or "TLS if available".
Mozilla Messaging has a list of email provider configuration information at the Mozilla ISP database that is used by the new account wizard added in Thunderbird 3.0. If the account wizard doesn't know about your email provider but it's listed in that database, that information was probably added too late for the current version of Thunderbird. In that case it's not as convenient, but you can still use that information to manually add an account.
If your email provider isn't listed please tell them about that database and suggest they add their configuration information.
- 1and1's instructions for using Netscape 7 with POP servers
- 1and1's instructions for using Netscape 7 with IMAP servers
- Use your email address as the username, and mail.adelphia.net for both the POP and SMTP server. Don't enable secure connections or authentication.
AT&T (aka SBC)
- AT&T's instructions for Thunderbird
- Mozillazine thread on "AT&T/SBC Yahoo's new email settings"
- AT&T's instructions on how to verify email settings in Thunderbird
- AT&T appears to resell Yahoo mail, providing access to Yahoo's POP and SMTP servers. They have thier own help pages though. Common problems appear to be not entering your email address as the username, not checking the "Use name and password" option for the SMTP server or checking the secure connection or authentication checkbox.
AOL / AIM
- Knowledge Base's instructions
- Instructions plus a good overview of its quirks / incompatibilities
- AOL's instructions
- For some unknown reason enabling SSL for the IMAP and/or the SMTP server doesn't work for some users. If this happens try a different mail server. If that still doesn't work, don't use a secure connection. Another common problem is forgetting to check "use name and password" for the SMTP server.
- Use your email address as the username, and mail.bigpond.com as the POP and SMTP server. Don't check the secure connection or secure authentication checkboxes.
- Bluebottle's instructions
BlueYonder (aka Telewest)
- BlueYonder's instructions for Outlook Express 6
- Don't use the email alias that you may have created in selfcare as your login name as the username.
- Email instructions in the BTOUsergroup FAQ
- Charter's instructions for Thunderbird
- Comcast's instructions
- Comcast's instructions state you should leave both "use secure authentication" and "use secure connection (SSL)" unchecked when configuring the POP account. Some users have enabled "secure authentication" and gotten it to sporadicly work. The SSL support seems to be reliable. It's recommended you use a secure connection (SSL) rather than secure authentication if you don't want to send the password in the clear when logging into the POP server.
- Comcast documents two SMTP configurations, a unsecure connection using port 25 and a secure connection using "TLS if available" and port 587. If you get a error message that the SMTP server may be unavailable or refusing SMTP connections there is a undocumented configuration that several users have gotten to work. Use port 465 , set "use secure connection" to SSL, check the authentication required box and provide your full Comcast address as the username.
- The Comcast spam filters limit messages to Comcast addresses to six recipients per second. This may occasionally cause new mail to you to be bounced, or prevent you from sending a message. When this problem occurs the sender will get a 4xx error message (temporary failure) and a link for instructions on how to solve the problem. 
- Comcast SMTP error codes
- Cox's instructions
- Dreamhost's instructions
- Dreamhost uses a Courier IMAP server. You need to change the maximum number of server connections to cache per the first paragraph at IMAP advanced account configuration.
- Common problems are entering your full email address as the username or using the webmail username instead of the email login name. Frequently your email login name is a letter followed followed by a bunch of numbers. If you occasionally temporarily lose a message, it's because you didn't change the maximum number of server connections to cache.
- Earthlink's instructions
- Earthlink's proprietary email client can prevent other email clients from getting new messages. See this Microsoft Knowledge Base article
- You need an account to access the email providers instructions. However, supposedly the POP server is pop.embarqmail.com , the SMTP server is smtp.embarqmail.com , you enter your email address as the username, and you should not check "use secure authentication".
- Fastmail's instructions
- Common problems are not using your email address as the username, or fiddling with the default settings in Tools -> Account Settings -> Server Settings -> Advanced because you're used to having to specify the IMAP server directory etc.
- Fastmail uses a Cyrus IMAP server, which treats everything as a subfolder of the Inbox. That means folders such as Sent Items and Junk Mail are child folders, rather than peers of the Inbox. While it's possible to work around this by changing how the IMAP server directory is specified in Tools -> Account Settings -> Server Settings -> Advanced, that usually causes the folder listing to display duplicate folders or creates other problems. 
- They don't have any instructions for Thunderbird, Mozilla or Netscape. It's probably easiest to adapt the Eudora instructions. Be careful with your 'dots' and 'dashes' when specifying usernames and mail servers. A username should use all dashes (i.e. userid-f2s-com), but the servers have dots (i.e. inmail.f2s.com and outmail.f2s.com).
- Fusemail's instructions for Thunderbird
- Generic account settings
- Knowledge Base's instructions
- Gmail's instructions
- Common problems are not configuring a SSL connection with port 995 for POP , not configuring a TLS connection using port 587 for SMTP, or not logging into Gmail webmail and telling it to enable POP. Gmail works well with Thunderbird, but it's quite common to have problems configuring it because it's not standard-compliant.
- GMX's instructions for creating a IMAP account using Thunderbird
- GMX's instructions for creating a POP account using Thunderbird
- GoDaddy's instructions
- Don't forget to configure a SMTP relay server in step 9, it's not sufficient to just enter the SMTP servers name and port in Outgoing Server (SMTP) Settings.
- Hughes's instructions for Mozilla
- Common problems are not authenticating your hughes.net email account (by logging into their webmail) before using Thunderbird, using .com instead of .net in the mail server, not using your email address as the username and configuring secure connections or authentication. If you were a DIRECWAY customer you can't use that username in the outgoing server settings, you have to setup a hughes.net account in www.myhughesnet.com .
- See this forum thread or this forum thread for more information.
- Inbox's instructions for Outlook Express 6
- Inbox's instructions on how to enable POP/SMTP access to your account
- Lavabit's instructions for Thunderbird
- Lycos basic only supports webmail, using httpmail. See Using webmail with Thunderbird .
- Lycos's instructions for Lycos plus
- It's unclear whether you have to use your ISPs SMTP server or can use smtp.mail.lycos.com on port 25 for Lycos plus.
- .Mac's instructions for Thunderbird
- Use the setup data for Outlook Express from the MobileMe Setup page. The main difference is that in Thunderbird you create an account by pressing the Add Account button in Tools -> Account Settings. Don't select "use secure authentication".
- MobileMe: Configuring third-party email applications has separate instructions for creating a Thunderbird account using me.com and mac.com addresses.
- In Thunderbird 3, a MobileMe account can be set up automatically. Once it is set, simply go to the SMTP settings to adjust it. For Connection Security to STARTTLS. By doing so, the defaul port changes automatically to 25. You will be able to send and receive emails with that minor change.
- Several ISPs offer MSN Premium accounts to their users instead of their own service (e.g. Qwest). Most only provide instructions for setting up these accounts in Microsoft products, but they will work in Thunderbird as well.
- Microsoft's instructions for Outlook. The instructions in method 2 give the information that is needed to configure Thunderbird.
- Note: For MSN Premium accounts to work in Thunderbird 1.5 and above you must change a pref in the Config Editor. network.ntlm.send-lm-response must be set to true - Bug 312344
- MyRealBox's instructions for Outlook Express
- Since you're running beta versions of Novell Netmail if the Thunderbird account suddenly stops working you may have run into a bug that they will fix within a day or two.
- NTLWorld's instructions for Outlook Express
- You use a email address that looks like firstname.lastname@example.org , pop.ntlworld.com as the POP3 server, and smtp.ntlworld.com as the SMTP server.
Outlook Web Access (OWA)
- Add-ons that support OWA
- It's difficult to get OWA working. It seems to frequently require tweaking supposedly "known good" scripts to get them to work.
- PeoplePC's settings for Outlook Express
- See the instructions under MSN Premium.
- Road Runner's Email help page
- Road Runner provides mail servers based on their customer's location. If you try to log in to the wrong server it will reject your password as if you had entered it incorrectly. Road Runner's email help page includes an "E-mail Quick Reference" box which shows users the correct servers based on that user's provider and location.
- Rogers' instructions
- Rogers has partnered with Yahoo, providing access to your rogers account via Yahoo's webmail but retaining their own pop and smtp servers. Common problems appear to be not entering your email address as the username, not checking the "Use name and password" option for the SMTP server or checking the secure connection or authentication checkbox.
- Sky's instructions for Outlook Express
- Don't check the checkbox for secure connection or authentication.
- Thier web site requires you to enter a valid email address in order to view email help pages.
- You can figure out some of the information you need from this forum thread . Try "TLS if available" and port 25 if you want to make a secure connection to the SMTP server.
- Telus's instructions
- Don't check the checkbox for secure connection or authentication. The troubleshooting section of the instructions mentions that you can get a "550 relaying mail is not allowed" error if you try to send a message using their SMTP server without being connected to the Internet using Telus. So it appears that you do not want to check "use name and password" in the SMTP settings. It also mentions a "The POP3 Server Responded: POP Lock Busy, Is Another Session Active" error , followed by a error about a bad password that can occur if there are two simultaneous attempts to access the mailbox. The workaround is to wait ten minutes.
- Tiscali UK's instructions for Thunderbird
- Tuffmail's instructions
Verizon -- the link below only takes you to Yahoo's Verizon tutorials -- Verizon does not support Thunderbird! Verizon's tech support will not address secure authentication, ssl, nor tls settings.
- Verizon Yahoo! Mail instructions
- DSLreport's Verizon email instructions
- Using webmail with Thunderbird
- Yahoo's instructions for Netscape
- Yahoo's instructions for Outlook Express
- If you can't send messages then you need to configure the SMTP server to create a secure connection using SSL and port 587.
- Yahoo.UK's instructions