diff --git a/FAQ.md b/FAQ.md
index 6ab419fb90..30d2653634 100644
--- a/FAQ.md
+++ b/FAQ.md
@@ -1204,6 +1204,8 @@ It is possible to configure a [regex](https://en.wikipedia.org/wiki/Regular_expr
 to match the username of an email address (the part before the @ sign).
 
 Note that the domain name (the parts after the @ sign) always needs to be equal to the domain name of the identity.
+if you specify the domain part in your expression, the pattern has to match the domain part of the identity, otherwise,
+the matching will always fail (except for the address of the identity itself).
 
 If you like to match the special purpose email addresses abc@example.com and xyx@example.com
 and like to have a fallback email address main@example.com as well, you could do something like this:
diff --git a/app/src/main/java/eu/faircode/email/EntityIdentity.java b/app/src/main/java/eu/faircode/email/EntityIdentity.java
index 35f5c54a3b..73e36037f9 100644
--- a/app/src/main/java/eu/faircode/email/EntityIdentity.java
+++ b/app/src/main/java/eu/faircode/email/EntityIdentity.java
@@ -154,7 +154,14 @@ public class EntityIdentity {
             if (user.equalsIgnoreCase(cemail[0]))
                 return true;
         } else {
-            if (Pattern.matches(sender_extra_regex, cother[0]))
+            /* match by regex
+             * if the expression contains @, assume the pattern also contains the domain part.
+             * if no @ is contained, assume only the local part should be matched.
+             * Domain part must match identity domain part in any case, else
+             * this is never reached ( see cother[1] comparison above)
+             */
+            String matchInput = (sender_extra_regex.contains("@") ? matchInput = other : cother[0];
+            if (Pattern.matches(sender_extra_regex, matchInput))
                 return true;
         }