diff --git a/scm-core/src/main/java/sonia/scm/user/EMail.java b/scm-core/src/main/java/sonia/scm/user/EMail.java
index 8da1377c94..e525b8d46c 100644
--- a/scm-core/src/main/java/sonia/scm/user/EMail.java
+++ b/scm-core/src/main/java/sonia/scm/user/EMail.java
@@ -26,6 +26,7 @@ package sonia.scm.user;
 
 import com.google.common.base.Strings;
 import sonia.scm.config.ScmConfiguration;
+import sonia.scm.util.ValidationUtil;
 
 import javax.inject.Inject;
 
@@ -50,7 +51,7 @@ public class EMail {
    */
   public String getMailOrFallback(User user) {
     if (Strings.isNullOrEmpty(user.getMail())) {
-      if (user.getId().contains("@")) {
+      if (isMailUsedAsId(user)) {
         return user.getId();
       } else {
         return createFallbackMail(user);
@@ -60,6 +61,10 @@ public class EMail {
     }
   }
 
+  private boolean isMailUsedAsId(User user) {
+    return ValidationUtil.isMailAddressValid(user.getId());
+  }
+
   private String createFallbackMail(User user) {
     return user.getId() + "@" + scmConfiguration.getMailDomainName();
   }