I want to share this ideas of provisioning / developing the ability to create "Contact Lists" & Contact Groups where as Mail User can add multiple Contacts and save that lists. this option is widely available on different platforms (hotmail, Yahoo, gmail, AOL etc.)
Example I can create a Contact List Called "Office Managers" where as I can add all manager level Contacts or email addresses.
and when I have to send email I don't have to manually chose 12 contacts individually but just in my New Mail  Window type the Contact List Name " Office Managers" and continue, with rest of the email (Subject and Body/ main message and just click send)

NOTE: This option should not only be Available in Webmail but also well integrated in EWS/ EAS.
in Well Know Mail Clients (Ms-Outlook 365, Ms-Outlook 2019 Apple Mail, IOS Mail) when EWS/ EAS Configured on the mail clients.