Generally vague out of context.

--The use of "feasibility of X" is strange without "the", I think ungrammatical for me (but fully comprehensible, like a newspaper headline).
--Clusterability isn't a word I'm familiar with, but I don't see why it can't be one. I can guess what it means. (=Clustered distribution)
--There should probably be a comma before "which", but that's not always adhered to even by native writers.
--"It" is awkward in the relative clause because it appears to be a resumptive pronoun, not found in English, except in particularly long sentences or awkward constructions, though here in an embedded conditional might be used by native speakers as well. I'd reverse the order of "is not obvious" and "if...", and then it would sound fine.
--"Mails" is an odd plural. It depends on exactly what is being referred to here. In normal usage, mail is a mass noun and cannot be pluralized. But in technical usage perhaps it is like "emails" which can be. I'd need to know the context.

Overall the sentence could be written in a much clearer way, though whatever context it was in might help a lot.