Save emails as files or PDFs in Mail on Mac
You can save email messages as files to use in other apps or as PDFs.
Choose how you want to save the messages.
Save messages as files: Choose File > Save As, then choose a format.
Rich Text Format retains formatting (such as bold and italics), but Plain Text does not. Raw Message Source saves a single message in .eml format.
Save messages as PDFs: Choose File > Export as PDF.
You can also save messages in .eml format by dragging them to your desktop. If you drag a conversation, the messages in it are saved as separate files.