lib-mail: message_address_write() - Always write <user@domain> as output

This is the standard format nowadays, so don't convert <user@domain> into
plain user@domain.

src/lib-mail/message-address.c

@@ -444,18 +444,8 @@ void message_address_write(string_t *str, const struct message_address *addr)
 			}
 
 			in_group = !in_group;
-		} else if ((addr->name == NULL || *addr->name == '\0') &&
-			   addr->route == NULL) {
-			/* no name and no route. use only mailbox@domain */
-			i_assert(addr->mailbox != NULL);
-
-			str_append_maybe_escape(str, addr->mailbox, FALSE);
-			if (addr->domain[0] != '\0') {
-				str_append_c(str, '@');
-				str_append(str, addr->domain);
-			}
 		} else {
-			/* name and/or route. use full <mailbox@domain> Name */
+			/* "Display Name" <mailbox@domain> */
 			i_assert(addr->mailbox != NULL);
 
 			if (addr->name != NULL) {

src/lib-mail/test-message-address.c

@@ -22,9 +22,9 @@ static void test_message_address(void)
 		const char *wanted_output;
 		struct message_address addr;
 	} tests[] = {
-		{ "user@domain", NULL,
+		{ "user@domain", "<user@domain>",
 		  { NULL, NULL, NULL, "user", "domain", FALSE } },
-		{ "<user@domain>", "user@domain",
+		{ "<user@domain>", NULL,
 		  { NULL, NULL, NULL, "user", "domain", FALSE } },
 		{ "foo bar <user@domain>", "\"foo bar\" <user@domain>",
 		  { NULL, "foo bar", NULL, "user", "domain", FALSE } },
@@ -44,7 +44,7 @@ static void test_message_address(void)
 		  { NULL, "hello", NULL, "user", "", TRUE } },
 		{ "hello <user>", "hello <user>",
 		  { NULL, "hello", NULL, "user", "", TRUE } },
-		{ "@domain", NULL,
+		{ "@domain", "<@domain>",
 		  { NULL, NULL, NULL, "", "domain", TRUE } },
 	};
 	static struct message_address group_prefix = {