@@ -0,0 +1,25 @@
+import re
+
+PATTERN = r"[a-zA-Z0-9._%+-]+@[a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+)*\.[a-zA-Z]{2,}"
+
+
+class Emails(list):
+    def __init__(self, addresses: list) -> None:
+        self.data = self.validate(addresses)
+        list.__init__(self, self.data)
+
+    @classmethod
+    def validate(cls, addresses: list) -> list:
+        if not all(isinstance(a, str) for a in addresses):
+            raise ValueError("All e-mail addresses must be strings")
+        for a in addresses:
+            if re.fullmatch(PATTERN, a) is None:
+                raise ValueError(f"Not a valid e-mail address: {a}")
+        # dict.fromkeys removes duplicates and keeps the order
+        return list(dict.fromkeys(addresses))
+
+    def __repr__(self) -> str:
+        return f"{self.__class__.__name__}({self.data})"
+
+    def __str__(self) -> str:
+        return f"{len(self.data)} e-mail(s): " + " | ".join(self.data)