You can use IFTTT (If This Then That) for this.
It is a cloud solution that is meant to couple various cloud services.
There is already a recipe that does exactly this. You do not need to enter your twitter handle or password. It uses an RSS feed from twitter which contains your keyword, when a new entry occurs an e-mail will be sent.
https://ifttt.com/recipes/68383-twitter-keyword-to-email
You can adjust this recipe to use a different RSS feed generated by different search results. To generate this RSS feed see the Advanced Search page on Twitter.