i have a field in the record page. When i click the EMAIL button on the record page, a pop-up is shown up. I should fetch the value of the field from the record and set it on the pop-up page. how can i do this? Could anyone please help me?

Did you create the email button or is it native NS? If it's native NS I don't think you'll be able to achieve this unless you can somehow employ an email template...

its a native EMAIL button on the Communications Subtab of a Transaction record.

Create a UE on

Message

. With great power comes great responsibility.

Might struggle to retrieve the value you want to use of you're on the message record. Kinda hard to tell from the requirement described.