To add an email other than gmail, you should first try the automatic setting of Desire HTC HD .. By default, HTC Desire HD using POP3 settings so make sure that support the use of a POP3 mail server .. If it fails Desire HD via POP3 settings, can be tried manual settings with the IMAP protocol .. Here are the steps IMAP settings in the Desire HD ..
Open Mail, then select Other (POP3/IMAP)
After New account to open, the contents of email address & password in accordance email settings
Select Manual Setup
After Incoming server settings screen appears, change the IMAP protocol so
SSL security change to the usual 993
Change the IMAP Server (just look at the settings for yahoo mail providers use imap.mail.yahoo.com .. .. others can also try setting it ..) and then select Next
Once the screen appears Outgoing server settings
STMP change so smtp.mail.yahoo.com
and replace securitynya to SSL, 465, continue to select Next