Question: I wonder if e-mail may be considered as evidence in a legal dispute, in any form whatsoever. E-mail is an old technique (the seventies last century) which is still being practiced? Such obsolete technology has several problems with security. It is trivial to manipulate or distort mail. A judge can not just accept it?
This scenario is for The Netherlands, you will have to check out your country for legal cases.
Answer: There are no rules in the Netherlands about the requirements that evidence must meet in order to have proof. Anything goes as long as the court considers that it proves that what the party says about contributing. (The only exception is the signature of: an autographed piece of paper, whether or not the solicitor. Of these, in principle, the courts should accept as evidence of what was agreed.) The court will never precede or surveys e-mail really is, or reject mail just because it is a mail. The general rule is, as long as the parties themselves do not point, everything can be discussed.
If the other party has a point, then the court must weigh the opinions and determine what it is most likely to occur. A pile of mail you get not just the table with "oh come that is forged, everyone knows that email is trivial to falsify". The court heard evidence that this is precisely forged emails are not mail in theory to falsify.
Proof is always in the context. An example. Alice lends Bob EUR 1200, and Bob put in the mail that he will pay back at 100 euros per month. Next, Bob 100 euros for three months with a definition "loan repayment". Then he stops. Alice complains to Bob, who now denies having signed a loan, saying that mail then introduces Alice, spoofed. That Bob will lose: the description shows that there is a loan, and it is only logical that there are agreements. Such mail is obviously the deal. Without further clarification from the court that mail will use to determine what the deal is
When Bob says that the loan was only 300 euros and that Alice is the amount "1200 euro" in the mail is forged, then Alice has a difficult situation. It is not inconceivable that someone claiming more than they deserve. Alice would be rectified by transfer to Bob in 1200 to show euro. That combined with the mail would be proof enough. (Therefore you must never lend a sum of money in cash.)
It is always a matter of weighting all the facts together. You can't say; It's mail so we don't look at it.