diff --git a/models/smtp.go b/models/smtp.go
index aeedce42..89796457 100644
--- a/models/smtp.go
+++ b/models/smtp.go
@@ -104,7 +104,7 @@ func (s *SMTP) Validate() error {
 
 // validateFromAddress validates
 func validateFromAddress(email string) bool {
-	r, _ := regexp.Compile("^([a-zA-Z0-9_\\-\\.]+)@([a-zA-Z0-9_\\-\\.]+)\\.([a-zA-Z]{2,5})$")
+	r, _ := regexp.Compile("^([a-zA-Z0-9_\\-\\.]+)@([a-zA-Z0-9_\\-\\.]+)\\.([a-zA-Z]{2,18})$")
 	return r.MatchString(email)
 }