Is an email admissible in courtOften yes, if it is relevant and can be authenticated, but the rules vary

What courts look for

In US federal courts, an item must be authenticated, meaning there is evidence it is what its proponent says it is (Federal Rule of Evidence 901). Rule 902(14) also allows data copied from an electronic device or file to be authenticated by a qualified person’s certification of a process of digital identification, such as a hash value. In the EU, eIDAS Article 46 says an electronic document cannot be refused as evidence solely because it is electronic.

Courts look at context: the full header, the sender and recipient accounts, other messages in the thread and whether anyone disputes that it is genuine. A screenshot alone is easier to challenge; see are screenshots legal evidence.