For agreements made by e-mail, text message or even written on paper, how can they be used as evidence in small claims court? For example if a plaintiff claimed a defendant owes him $100 for work completed. Plaintiff prints out an email from defendant showing the defendant agreed to this. What if the defendant just denies having sent such an email? In theory it could be easy for either party to be lying, so would the court order a subpoena to the email server to see what their records hold? This seems awfully in efficient? What if parts of the agreement are made over other messaging apps?
Physical evidence in a court does not stand on its own: it always needs a witness to introduce it and say how they know it is true.
A contract is a "meeting of minds": two parties "agree" about what their obligations are going to be. In this context "agree" means "have the same idea in their minds", in the same sense that you and I agree that they sky is blue.
Written records of a contract exist to record exactly what the agreement was. Signatures and the like are used as evidence that it was this version of the contract that was agreed and not something else. This is why verbal contracts are still binding: a meeting of minds was reached. If a dispute arises then the court will have to try to figure out what was actually agreed based on the testimony of the two parties, bearing in mind that one or the other may honestly misremember.
In your hypothetical case the printed message is evidence, and hence forgetfulness can be eliminated. If one party denies sending a message that the other claims to have received then there are only three possibilities:
The Plaintiff has committed perjury.
The Defendant has committed perjury.
Some third party has sent the message with the intent of misleading the recipient.
The latter is usually unlikely. At this point if neither party will back down it would probably turn into a criminal case to identify the perjurer. Since perjury is a serious crime search warrants and forensic investigation would presumably follow.
Emails pick up a log of which computers they passed through and when. You can probably see them using a "View all headers" or similar option on your email client. Here is a sample:
Received: from us2.mx.mailhostbox.com (inbound4.mailhostbox.aus-tx.colo [172.16.214.82]) by us2.mailforward.mailhostbox.com (Postfix) with ESMTP id 123456789 for <Joe@bloggs.com>; Thu, 30 May 2019 15:23:53 +0000 (GMT)
There should be a log of that message having been forwarded which can be verified with the company running the server (although log expiry will be an issue). The same will go for each stage, including the recipient's ISP.
This is why Email has an option for a Read Reciept, which is a feature that sends a short email back to sender when the recipieant(s) open and read the reciept. A quick way to get a witness to you sending an e-mail is to send it to a third party using a BCC. This works like a CC (Carbon Copy) e-mail, but does not notifiy any of the recipients of the BCC recipients, with exception to the individual BCC reciever. (If Alice send Bob an email and BCCs Charley and Diane), Bob will only see his name, Charlie sees his name and Bob's, but not Diane's). You will see all recipients.
Depending on what the email is being used to establish will play a big role. For example, if you have a duty to send it, than you need only show the logs and maybe the BCC. As it is sent and at a certain time. If you have a duty to not react until after he has read it, Submit with a read receipt. If he is claiming that he did not see the e-mail, you should probably look for an outgoing e-mail from his mail box . Again, a read reciept on an e-mail chain unrelated could be effective to a verble yes no about