when forwarding emails from my phone the time and date is sometimes removed

It has come to my attention that when forwarding an email received on my iphone 5s the time and date is sometimes removed and cannot be seen by the recipient. The format of the other data, i.e sender and c.c is also changed. This has led to an accusation that the document has been tampered with and has legal implications going forward with whether the iphone is a trusted means of transfer of emails. The email when read on exchange server contains the full time/date data? can anyone help?