Creating Distribution Lists in Outlook
These basic instructions came from Microsoft
Please note that each DL has a limited size that restricts it to a few hundred entries, which may not be enough for some. In cases such as this, it’s recommended that you instead use a database in either Excel or Access. This not only is much easier to update but you can then use this for other mail merge options in Word, for example. You can either copy/paste these names into the TO field (limited to about 1000 addresses) or create an email merge from within Word.