Step 1: Go to Home > Manage > <Select the distribution list > for that you want to configure the restriction then click on Owners > Add > Put the owner email id > OK. The following is an example of [email protected] as the owner of the [email protected] distribution list.
Note: If your Distribution List already has an owner then you can skip the first step.
Step 2: Please login to the webmail to the owner of that distribution list then Go to Contacts > Distribution Lists > Select the distribution list and right-click on it > Edit Distribution List
Step 3: Go to Distribution List Properties > On the 'Mail' section select "only these users can send to this list" > put the specific email ids only who can send emails to the distribution list > Save