Is there any way to delete emails before a particular date?

I can search the emails before a particular date using the search builder.

But selecting emails all the time and deleting them would be a time taking process since the account is more than 2 GB.

I am deleting emails because, since my account is more than 2 GB, I could not get connected to the Outlook.

Also, I get the problem that my Firefox crashes. Not sure whether it is because the account holds more than 2 GB or due to some extension problem in the Firefox.