Trigger Drupal Rule Based on Taxonomy Term
When you say the content "matches" the term, do you mean the content has a field to select that term, and you want the email to send when the content has been tagged with that term?

If thats the case... 


Create a new condition "Entity Has Field"
Choose the taxonomy field.
Create a new condition "if taxonomy field == taxonomy name"
Create action to send mail to user of a role.