add !pm relay - per-mailbox relay config

utils/utils.go

@@ -2,6 +2,7 @@ package utils
 
 import (
 	"net"
+	"net/url"
 	"sort"
 	"strconv"
 	"strings"
@@ -40,6 +41,15 @@ func SanitizeDomain(domain string) string {
 	return domains[0]
 }
 
+// SanitizeURL checks that input URL is valid
+func SanitizeURL(str string) string {
+	parsed, err := url.Parse(str)
+	if err != nil {
+		return ""
+	}
+	return parsed.String()
+}
+
 // Bool converts string to boolean
 func Bool(str string) bool {
 	str = strings.ToLower(str)