Google Apps Script to enumerate all email addresses active on a domain

enumerate_emails.gs

/***
* INSTRUCTIONS
* 1. Change the domain in the CONFIG below to your domain.
* 2. Logged in as a Google Workspace admin for the domain of interest, create a new Google Sheet in the Workspace.
* 3. In the sheet, select the menu Extentions > Apps Scripts
* 4. In the script editor, add a Service (with the + in "Services") and add the "AdminDirectory" API.
* 5. Copy/paste this code into the CODE section
* 6. Save & Run the code
* 7. The sheet should be updated with a full inventory of your domain's email address surface area!
*/

// CONFIG
const domain = 'showcaseidx.com'; // Replace with your GSuite domain

// Clear the sheet and set headers
let sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
sheet.clear();
sheet.appendRow(['account type', 'account name', 'email address', 'is alias?', 'DL members']);
listAllUserAliases()
listAllGroupAliases()

function listAllUserAliases() {  
  var users = AdminDirectory.Users.list({domain: domain, viewType: 'admin_view'}).users;
  
  if (users) {
    for (var i = 0; i < users.length; i++) {
      var user = users[i];
      console.log(`[${user.primaryEmail}] Found user...`)
      if (user.suspended) {
        console.log(`[${user.primaryEmail}] User suspended, skipping...`)
        continue
      }

      // Append the primary email of the user
      sheet.appendRow(['user', user.primaryEmail, user.primaryEmail, false]);
      
      // Check if aliases are available for the user
      if (user.aliases && user.aliases.length > 0) {
        console.log(`[${user.primaryEmail}] Found ${user.aliases.length} aliases.`)
        for (var j = 0; j < user.aliases.length; j++) {
          sheet.appendRow(['user', user.primaryEmail, user.aliases[j], true]);
        }
      } else {
        console.log(`[${user.primaryEmail}] Found 0 aliases.`)
      }
    }
  }
}

function getActiveGroupMembers(groupEmail)
{
    var rows = [];
    var pageToken, page;
    do {
        page = AdminDirectory.Members.list(groupEmail,
        {
            domainName: domain,
            maxResults: 500,
            pageToken: pageToken,
        });
        var members = page.members
        if (members)
        {
            for (var i = 0; i < members.length; i++)
            {
                var member = members[i];
                rows.push(member);
            }
        }
        pageToken = page.nextPageToken;
    } while (pageToken);
    return rows;
}


function listAllGroupAliases() {
  var groups = AdminDirectory.Groups.list({domain: domain}).groups;
  
  if (groups) {
    for (var i = 0; i < groups.length; i++) {
      var group = groups[i];
      console.log(`[${group.email}] Found group...`)

      // gather group membership list      
      const groupMembers = getActiveGroupMembers(group.email);
      const groupMemberEmails = groupMembers.reduce( (carry, currentVal) => {
        carry.push(currentVal.email);
        return carry;
      }, [])
      // Add primary group to sheet
      sheet.appendRow(['group', group.email, group.email, false, groupMemberEmails.join(',')]);

      // Check if aliases are available for the group
      if (group.aliases && group.aliases.length > 0) {
        console.log(`[${group.email}] Found ${group.aliases.length} aliases.`)
        for (var j = 0; j < group.aliases.length; j++) {
          sheet.appendRow(['group', group.email, group.aliases[j], true]);
        }
      } else {
        console.log(`[${group.email}] Found 0 alises.`)
      }
    }
  }
}