How to use commas as separators for multiple email recipients
By default, if you try to add addresses using commas as separators, you see the message that Outlook does not recognize addresses:
To add commas as separators in Outlook, do the following:
1. On the File tab, click Options:
2. On the Mail tab, under Send messages, select the Commas can be used to separate multiple message recipients checkbox:
3. Select OK.
Now you can use commas as separators. Outlook automatically checks names and changes commas to semicolons: