Some web-base email applications allow you to export contacts in text (comma-separated) or LDIF formats. Check your ISP's documentation for more information. To import contacts into Thunderbird, select Tools | Import… and follow the instructions on the screen. LDIF is the preferred import format.

eldene said

Mozilla Thunderbird is a new program for me for e-mail. I have an entire address book on an old POP server. Do I have to keep on manually adding to this new address book or is there a way to download my Contacts information to this new IMAP server?

Thanks so much for the help. I am pleased to say that I followed your instructions and it worked perfectly. It transferred all my contacts from my old program in the right format for the new Thunderbird IMap program. I am so pleased as it saved me so much work.