Thunderbird supports two connection methods for accessing your email: IMAP and POP3. Instructions for each method are provided, but they shouldn't be used simultaneously on an individual computer. As such, please choose one method or the other for each computer or smart device based on your needs.
POP3 downloads all email to the client (your) computer. POP3 is commonly used when email is only accessed from one computer but can be used in more complex situations if you wish to archive your own mail. When using POP3, you can delete mail off the CICI server, but it will remain accessible in Thunderbird if already downloaded.Click here for POP3 instructions
IMAP stores all email on the CICI server. IMAP is best used for email accounts which will be accessed from multiple devices or multiple locations. With IMAP, mail which is deleted off the CICI server either through webmail or an appropriately configured client will no longer be accessible using IMAP, Webmail, or any computer using POP3 which hasn't downloaded it already. As an advantage, using IMAP allows multiple mail programs and multiple devices to see a consistent view of your email.Click here for IMAP instructions