Open Excel and paste the email addresses into the A column
Click on the B column and add this text into the excel formula bar: =A1&","
Double click the small dot in the bottom corner of the B cell.
Your email addresses will now all move over with commas – which is how Mac Mail formats and validates email addresses when you add them. You can now copy and paste the B column into mail email field.
Comments
This was amazingly helpful for me! Thanks.