Often times these emails go directly to HR, who ultimately don’t care at all about your portfolio. They are looking for keywords, and as mentioned often times for interns they will look to see if you are a student in a 4 year program and where in the program you are.
The main reason for this is (and I do the same when hiring interns) is I want to contribute to a students growth, and I also don’t want hard feelings in 3-4 months when they have to go back to school. Having time remaining on their academic term makes this fairly easy.
When I get intern applications from someone who is 4 years out of school I may still look at their portfolio, but I view it with the standards I would expect from a new grad, not from a Sophomore or Jr. design student. Even then, if they have a good portfolio I will still defer them behind current students. (Personally I would rather every student gets a chance to do 1 internship than favoring students who do 3 or 4).