Sending Mails with random samples

Hello Experts:

I come to you (this is my first time) because we're being requested with something that we haven't done and maybe somebody can guide me through this.

Our Marketing team is requesting that we send 4 different mails in the same launching but using random samples of our base. that is:

In the same launching  25% of our base would receive mail 1 25% would received mail 2 etc. and the samples should be different one from the other

Is there a function in RESPONSYS  to use for these kind of requets? ¿Could You share with me the best way to approach such request?