diff --git a/app/dashboard/views/custom_alias.py b/app/dashboard/views/custom_alias.py
index ec8fb308..0d82cc25 100644
--- a/app/dashboard/views/custom_alias.py
+++ b/app/dashboard/views/custom_alias.py
@@ -175,20 +175,29 @@ def verify_prefix_suffix(user, alias_prefix, alias_suffix) -> bool:
 
     # make sure alias_suffix is either .random_word@simplelogin.co or @my-domain.com
     alias_suffix = alias_suffix.strip()
+    # alias_domain_prefix is either a .random_word or ""
     alias_domain_prefix, alias_domain = alias_suffix.split("@", 1)
 
-    if alias_domain_prefix:
-        if not alias_domain_prefix.startswith(".") or len(alias_domain_prefix) < 2:
-            LOG.exception(
-                "nonsensical alias suffix %s, user %s", alias_domain_prefix, user
-            )
+    # alias_domain must be either one of user custom domains or built-in domains
+    if alias_domain not in user_custom_domains and alias_domain not in ALIAS_DOMAINS:
+        LOG.exception("wrong alias suffix %s, user %s", alias_suffix, user)
+        return False
+
+    # built-in domain case:
+    # 1) alias_suffix must start with "." and
+    # 2) alias_domain_prefix must come from the word list
+    if alias_domain in ALIAS_DOMAINS and alias_domain not in user_custom_domains:
+        if not alias_domain_prefix.startswith("."):
+            LOG.exception("User %s submits a wrong alias suffix %s", user, alias_suffix)
             return False
 
-        if (
-            alias_domain not in user_custom_domains
-            and alias_domain not in ALIAS_DOMAINS
-        ):
-            LOG.exception("wrong alias suffix %s, user %s", alias_suffix, user)
+        random_word_part = alias_domain_prefix[1:]
+        if not word_exist(random_word_part):
+            LOG.exception(
+                "alias suffix %s needs to start with a random word, user %s",
+                alias_suffix,
+                user,
+            )
             return False
     else:
         if alias_domain not in user_custom_domains: