Yes, its possible.
It is necessary that you get access to the mailbox. This can be done with PHP. Once you have this, all you have to do is but a bulk SMS account and setup the API with your script.
Create Your Own Mail Script With PHP and IMAP
PHP: IMAP - Manual
If your mail provider does not give IMAP or POP3 access, you can buy a domain name for Rs. 400 per year, and hosting for 1000 per year. Bulk SMS gateway will cost you 2 or 3 K per year again.
Best is to check if you email provider is giving such features at any premium cost.