According to Wikipedia, Yahoo has free IMAP services.
"Free IMAP and SMTPs access
It is possible to get direct IMAP access without signing up for paid access nor using software like YPOPs! or FreePOPs. Yahoo operates IMAP servers (imap.mail.yahoo.com in particular), which are globally accessible. However they require a specific, but non-standard IMAP command to be sent before login is done. The command is: “ID ("GUID" "1")” and it is relatively easy to modify any email client to send it. In fact this is the method currently employed by YPOPSs! and FreePOPs. There are modified version of Mutt and Mozilla Thunderbird available that send this command.[23]
There is also an IMAPs server running at imap-ssl.mail.yahoo.com. It is using SSL on the standard port 993.
In addition it is also possible to send mail through mail clients as yahoo also operates an SMTP server (smtp.mail.yahoo.com). It is necessary to enable SSL through port 465. The username is the user's Yahoo mail address and the password is the same as for webmail access, this applies to both IMAP and SMTPs access.yahoo mail address and th e password is the same as for webmail access, the applies to both IMAP and amtps access."
"Free IMAP and SMTPs access
It is possible to get direct IMAP access without signing up for paid access nor using software like YPOPs! or FreePOPs. Yahoo operates IMAP servers (imap.mail.yahoo.com in particular), which are globally accessible. However they require a specific, but non-standard IMAP command to be sent before login is done. The command is: “ID ("GUID" "1")” and it is relatively easy to modify any email client to send it. In fact this is the method currently employed by YPOPSs! and FreePOPs. There are modified version of Mutt and Mozilla Thunderbird available that send this command.[23]
There is also an IMAPs server running at imap-ssl.mail.yahoo.com. It is using SSL on the standard port 993.
In addition it is also possible to send mail through mail clients as yahoo also operates an SMTP server (smtp.mail.yahoo.com). It is necessary to enable SSL through port 465. The username is the user's Yahoo mail address and the password is the same as for webmail access, this applies to both IMAP and SMTPs access.yahoo mail address and th e password is the same as for webmail access, the applies to both IMAP and amtps access."