Probably best to get a testing kit from e.g. DanceSafe[0] to at least confirm the stuff you've bought has MDMA in it. It is not uncommon for meth or other stuff (2C-B, or just inert filler) to be sold as MDMA.

(For the pedants: the positive test for the presence of MDMA does not prove that the substance isn't adulterated, but it's certainly better than a negative result.)

[0]: https://dancesafe.org/