Decide what the record must show
An EML file commonly stores one email message with header fields and body content. A PDF turns that message into a document for reading or filing, but the page view is not a substitute for the original mail data. Before converting, decide whether the record needs only the visible body or also technical headers, routing information, and attachments.
For an ordinary correspondence copy, the sender, recipients, date, subject, and body may be enough. For an investigation, legal hold, or formal archive, those details might not satisfy the required evidence process. Keep the original EML and ask the responsible records or legal team how source messages must be preserved.