support "domain aliases" (@domain => @domain aliases)

This seemed to already be technically supported but the validation is now stricter and the admin is more helpful:

* Postfix seems to allow @domain.tld as an alias destination address but only if it is the only destination address (see the virtual man page).
 * Allow @domain.tld if it is the whole destination address string.
 * Otherwise, do not allow email addresses without local parts in the destination.
* In the admin, add a third tab for making it clear how to add a domain alias.

closes #265

management/mailconfig.py

@@ -15,7 +15,7 @@ def validate_email(email, mode=None):
 	if mode == 'user':
 		# For Dovecot's benefit, only allow basic characters.
 		ATEXT = r'[\w\-]'
-	elif mode == 'alias':
+	elif mode in (None, 'alias'):
 		# For aliases, we can allow any valid email address.
 		# Based on RFC 2822 and https://github.com/SyrusAkbary/validate_email/blob/master/validate_email.py,
 		# these characters are permitted in email addresses.
@@ -27,7 +27,8 @@ def validate_email(email, mode=None):
 	DOT_ATOM_TEXT_LOCAL = ATEXT + r'+(?:\.' + ATEXT + r'+)*'
 	if mode == 'alias':
 		# For aliases, Postfix accepts '@domain.tld' format for
-		# catch-all addresses. Make the local part optional.
+		# catch-all addresses on the source side and domain aliases
+		# on the destination side. Make the local part optional.
 		DOT_ATOM_TEXT_LOCAL = '(?:' + DOT_ATOM_TEXT_LOCAL + ')?'
 
 	# as above, but we can require that the host part have at least
@@ -356,19 +357,28 @@ def add_mail_alias(source, destination, env, update_if_exists=False, do_kick=Tru
 	if not validate_email(source, mode='alias'):
 		return ("Invalid incoming email address (%s)." % source, 400)
 
-	# parse comma and \n-separated destination emails & validate
+	# validate destination
 	dests = []
-	for line in destination.split("\n"):
+	destination = destination.strip()
-		for email in line.split(","):
+	if validate_email(destination, mode='alias'):
-			email = email.strip()
+		# Oostfix allows a single @domain.tld as the destination, which means
-			if email == "": continue
+		# the local part on the address is preserved in the rewrite.
-			if not validate_email(email, mode='alias'):
+		dests.append(destination)
-				return ("Invalid destination email address (%s)." % email, 400)
+	else:
-			dests.append(email)
+		# Parse comma and \n-separated destination emails & validate. In this
+		# case, the recipients must be complete email addresses.
+		for line in destination.split("\n"):
+			for email in line.split(","):
+				email = email.strip()
+				if email == "": continue
+				if not validate_email(email):
+					return ("Invalid destination email address (%s)." % email, 400)
+				dests.append(email)
 	if len(destination) == 0:
 		return ("No destination email address(es) provided.", 400)
 	destination = ",".join(dests)
 
+	# save to db
 	conn, c = open_database(env, with_connection=True)
 	try:
 		c.execute("INSERT INTO aliases (source, destination) VALUES (?, ?)", (source, destination))

management/templates/aliases.html

@@ -13,22 +13,26 @@
   <div class="form-group">
     <div class="col-sm-offset-1 col-sm-11">
       <div id="alias_type_buttons" class="btn-group btn-group-xs">
-        <button type="button" class="btn btn-default active">Regular</button>
+        <button type="button" class="btn btn-default active" data-mode="regular">Regular</button>
-        <button type="button" class="btn btn-default">Catch-All</button>
+        <button type="button" class="btn btn-default" data-mode="catchall">Catch-All</button>
+        <button type="button" class="btn btn-default" data-mode="domainalias">Domain Alias</button>
+      </div>
+      <div id="alias_mode_info" class="text-info small" style="display: none; margin: .5em 0 0 0;">
+        <span class="catchall hidden">A catch-all alias captures all otherwise unmatched email to a domain. Enter just a part of an email address starting with the @-sign.</span>
+        <span class="domainalias hidden">A domain alias forwards all otherwise unmatched mail from one domain to another domain, preserving the part before the @-sign.</span>
       </div>
-      <div id="alias_catchall_info" class="text-info small" style="display: none; margin: .5em 0 0 0;">A catch-all alias captures all otherwise unmatched email to a domain. Enter just a part of an email address starting with the @-sign.</div>
     </div>
   </div>
   <div class="form-group">
     <label for="addaliasEmail" class="col-sm-1 control-label">Alias</label>
     <div class="col-sm-10">
-      <input type="email" class="form-control" id="addaliasEmail" placeholder="incoming email address (you@yourdomain.com)">
+      <input type="email" class="form-control" id="addaliasEmail">
     </div>
   </div>
   <div class="form-group">
     <label for="addaliasTargets" class="col-sm-1 control-label">Forward To</label>
     <div class="col-sm-10">
-      <textarea class="form-control" rows="3" id="addaliasTargets" placeholder="forward to these email addresses (one per line or separated by commas)"></textarea>
+      <textarea class="form-control" rows="3" id="addaliasTargets"></textarea>
     </div>
   </div>
   <div class="form-group">
@@ -106,16 +110,28 @@ function show_aliases() {
     $('#alias_type_buttons button').off('click').click(function() {
       $('#alias_type_buttons button').removeClass('active');
       $(this).addClass('active');
-      if ($(this).text() == "Regular") {
+      if ($(this).attr('data-mode') == "regular") {
         $('#addaliasEmail').attr('type', 'email');
-        $('#addaliasEmail').attr('placeholder', 'incoming email address (you@yourdomain.com)');
+        $('#addaliasEmail').attr('placeholder', 'incoming email address (e.g. you@yourdomain.com)');
-        $('#alias_catchall_info').slideUp();
+	$('#addaliasTargets').attr('placeholder', 'forward to these email addresses (one per line or separated by commas)');
-      } else {
+        $('#alias_mode_info').slideUp();
+      } else if ($(this).attr('data-mode') == "catchall") {
         $('#addaliasEmail').attr('type', 'text');
-        $('#addaliasEmail').attr('placeholder', 'incoming catch-all address (@yourdomain.com)');
+        $('#addaliasEmail').attr('placeholder', 'incoming catch-all address (e.g. @yourdomain.com)');
-        $('#alias_catchall_info').slideDown();
+	$('#addaliasTargets').attr('placeholder', 'forward to these email addresses (one per line or separated by commas)');
+        $('#alias_mode_info').slideDown();
+        $('#alias_mode_info span').addClass('hidden');
+        $('#alias_mode_info span.catchall').removeClass('hidden');
+      } else if ($(this).attr('data-mode') == "domainalias") {
+        $('#addaliasEmail').attr('type', 'text');
+        $('#addaliasEmail').attr('placeholder', 'incoming domain (@yourdomain.com)');
+        $('#addaliasTargets').attr('placeholder', 'forward to domain (@yourdomain.com)');
+        $('#alias_mode_info').slideDown();
+        $('#alias_mode_info span').addClass('hidden');
+        $('#alias_mode_info span.domainalias').removeClass('hidden');
       }
     })
+    $('#alias_type_buttons button[data-mode="regular"]').click(); // init
   })
 }
 
@@ -166,6 +182,12 @@ function aliases_edit(elem) {
   $("#addaliasEmail").val(email);
   $("#addaliasTargets").val(targets);
   $('#add-alias-button').text('Update');
+  if (email.charAt(0) == '@' && targets.charAt(0) == '@')
+    $('#alias_type_buttons button[data-mode="domainalias"]').click();
+  else if (email.charAt(0) == '@')
+    $('#alias_type_buttons button[data-mode="catchall"]').click();
+  else
+    $('#alias_type_buttons button[data-mode="regular"]').click();
   $('body').animate({ scrollTop: 0 })
 }