Chunghwa almost but not quite has email to sms service. What you have to do first is get a hinet email-only account. This will cost NT80 per month. With this account you can the use this program or your own:
to send messages. There used to a web page you could use, but it has either been moved or discontinued. The backend server still works though, so you can write a program to convert and relay your mail. Your email account will get charged a nominal fee per message, something around 0.5NT per message. I have a perl script that does this if anyone is interested.
I would not recommend doing this though. As others have mentioned, your email to sms address will become a spam magnet. I turned mine off middle of last year because it was too much trouble.