Hi,
You should be able to do a copy / paste BUT it depends on your mail system & how email addresses are separated - some use space, others comma, other semi-colon.
Do you know which one your email uses?
If you want you can send the excel sheet to me & I'll get the list formatted for you.
Otherwise highlight the cells in the excel spreadsheet with the email addresses you require, click on the menu item "edit" up top, then click "copy". Then in your email, click on where you enter the email address & click "Edit" then "paste" - your email addresses will be pasted in then. BUT it depends on your email whether it separates addresses by space/comma/semi-colon etc.