Filing email - as evidence -

Email is admissible evidence. It will be checked and questioned like any other and so its strength will depend upon the whole chain of events, admissions and denials etc. ideally, it should be on the company's domain/ registered email ids for consumer complaints.

As per sec 65 B of Evidence Act electronic evidences are admissible in evidence in any court,tribunal or forum.

65B. Admissibility of electronic records -

¹65B. Admissibility of electronic records.- (1) Notwithstanding anything contained in this Act, any information contained in an electronic record which is printed on a paper, stored, recorded or copied in optical or magnetic media produced by a computer (hereinafter referred to as the computer output) shall be deemed to be also a document, if the conditions mentioned in this section are satisfied in relation to the information and computer in question and shall be admissible in any proceedings, without further proof or production of the original, as evidence of any contents of the original or of any fact stated therein of which direct evidence would be admissible.

Yes it is admissible subject to the conditions of the section 65B of IE Act.  You may discuss with your lawyer and go ahead with the evidence.

E-mail  is a documentary evidence and documentary evidence is admissible according to Evidence Act.