Probable N6-methyltransferase that methylates adenosine residues of some mRNAs. N6-methyladenosine (m6A), which is present at internal sites of some mRNAs, may play a role in the efficiency of mRNA splicing, transport or translation (By similarity). an adenosine in mRNA + S-adenosyl-L-methionine = an N(6)-methyladenosine in mRNA + H(+) + S-adenosyl-L-homocysteine Belongs to the MT-A70-like family.