diff --git a/src/ldap.js b/src/ldap.js
index b0ff56a86..a1afd479b 100644
--- a/src/ldap.js
+++ b/src/ldap.js
@@ -674,13 +674,13 @@ function start(callback) {
     gServer.bind('ou=users,dc=cloudron', authenticateApp, authenticateUser, authorizeUserForApp);
 
     // http://www.ietf.org/proceedings/43/I-D/draft-srivastava-ldap-mail-00.txt
-    gServer.search('ou=mailboxes,dc=cloudron', mailboxSearch); // haraka, dovecot
+    gServer.search('ou=mailboxes,dc=cloudron', mailboxSearch); // haraka (address translation), dovecot (LMTP)
     gServer.bind('ou=mailboxes,dc=cloudron', authenticateUserMailbox); // apps like sogo can use domain=${domain} to authenticate a mailbox
     gServer.search('ou=mailaliases,dc=cloudron', mailAliasSearch); // haraka
     gServer.search('ou=mailinglists,dc=cloudron', mailingListSearch); // haraka
 
-    gServer.bind('ou=recvmail,dc=cloudron', authenticateMailAddon); // dovecot
-    gServer.bind('ou=sendmail,dc=cloudron', authenticateMailAddon); // haraka
+    gServer.bind('ou=recvmail,dc=cloudron', authenticateMailAddon); // dovecot (IMAP auth)
+    gServer.bind('ou=sendmail,dc=cloudron', authenticateMailAddon); // haraka (MSA auth)
 
     gServer.bind('ou=sftp,dc=cloudron', authenticateSftp);    // sftp
     gServer.search('ou=sftp,dc=cloudron', loadSftpConfig, userSearchSftp);