diff --git a/chatom/backend.py b/chatom/backend.py
index 9cc0673..8174eaa 100644
--- a/chatom/backend.py
+++ b/chatom/backend.py
@@ -1,24 +1,46 @@
 from typing import Literal, Union
 
 DISCORD = "discord"
+EMAIL = "email"
+IRC = "irc"
+MATRIX = "matrix"
 MATTERMOST = "mattermost"
 MESSENGER = "messenger"
 SLACK = "slack"
+SYMPHONY = "symphony"
 TEAMS = "teams"
 TELEGRAM = "telegram"
 WHATSAPP = "whatsapp"
 ZULIP = "zulip"
 
-Backend = Union[
+BACKEND = Union[
     Literal[DISCORD],
+    Literal[EMAIL],
+    Literal[IRC],
+    Literal[MATRIX],
     Literal[MATTERMOST],
     Literal[MESSENGER],
     Literal[SLACK],
+    Literal[SYMPHONY],
     Literal[TEAMS],
     Literal[TELEGRAM],
     Literal[WHATSAPP],
     Literal[ZULIP],
     str,
 ]
+ALL_BACKENDS = [
+    DISCORD,
+    EMAIL,
+    IRC,
+    MATRIX,
+    MATTERMOST,
+    MESSENGER,
+    SLACK,
+    SYMPHONY,
+    TEAMS,
+    TELEGRAM,
+    WHATSAPP,
+    ZULIP,
+]
 
-__all__ = ("Backend", "DISCORD", "MATTERMOST", "MESSENGER", "SLACK", "TEAMS", "TELEGRAM", "WHATSAPP", "ZULIP")
+__all__ = ("BACKEND", "DISCORD", "MATTERMOST", "MESSENGER", "SLACK", "SYMPHONY", "TEAMS", "TELEGRAM", "WHATSAPP", "ZULIP")
diff --git a/chatom/format/__init__.py b/chatom/format/__init__.py
index d17f147..534827e 100644
--- a/chatom/format/__init__.py
+++ b/chatom/format/__init__.py
@@ -1,3 +1,4 @@
 from .message import *
 from .table import *
 from .text import *
+from .variant import *
diff --git a/chatom/mention.py b/chatom/mention.py
index e69de29..a5a0171 100644
--- a/chatom/mention.py
+++ b/chatom/mention.py
@@ -0,0 +1,42 @@
+from .backend import BACKEND
+from .user import User
+
+
+def mention_user(user: User, backend: BACKEND) -> str:
+    """Generate a mention string for a user based on the backend platform.
+
+    Args:
+        user (User): The user to mention.
+        backend (BACKEND): The backend platform.
+
+    Returns:
+        str: The formatted mention string.
+    """
+    match backend:
+        case "discord":
+            return f"<@!{user.id}>"
+        case "email":
+            return f"<a href='mailto:{user.email}'>{user.name}</a>" if user.email else user.name
+        case "irc":
+            return f"{user.handle}" if user.handle else user.name
+        case "matrix":
+            return f"@{user.handle}:matrix.org" if user.handle else user.name
+        case "mattermost":
+            return f"@{user.handle}" if user.handle else user.name
+        case "messenger":
+            return f"@{user.name}"
+        case "slack":
+            return f"<@{user.id}>"
+        case "teams":
+            return f"<at>{user.name}</at>"
+        case "telegram":
+            return f"@{user.handle}" if user.handle else user.name
+        case "symphony":
+            return f"@{user.name}"
+        case "whatsapp":
+            return f"@{user.name}"
+        case "zulip":
+            return f"@**{user.name}**"
+        case _:
+            # Fallback to full name if no specific format is defined
+            return user.name
diff --git a/chatom/tests/test_backend.py b/chatom/tests/test_backend.py
new file mode 100644
index 0000000..84864da
--- /dev/null
+++ b/chatom/tests/test_backend.py
@@ -0,0 +1,10 @@
+from typing import Literal
+
+
+class TestBackend:
+    def test_all_backends_listed(self):
+        from chatom.backend import ALL_BACKENDS, BACKEND
+
+        # Ensure that ALL_BACKENDS actually has all backends
+        for backend in ALL_BACKENDS:
+            assert Literal[backend] in BACKEND.__args__
diff --git a/chatom/tests/test_mention.py b/chatom/tests/test_mention.py
new file mode 100644
index 0000000..a0fea6a
--- /dev/null
+++ b/chatom/tests/test_mention.py
@@ -0,0 +1,32 @@
+import pytest
+
+from chatom.mention import mention_user
+from chatom.user import User
+
+
+class TestMention:
+    @pytest.mark.parametrize(
+        "user,backend,expected",
+        [
+            (User(handle="jane_doe", id="456", name="Jane Doe"), "discord", "<@!456>"),
+            (User(handle="", id="789", name="Alice"), "email", "Alice"),
+            (User(handle="", id="101", name="Bob", email="bob@example.com"), "email", "<a href='mailto:bob@example.com'>Bob</a>"),
+            (User(handle="charlie", id="112", name="Charlie"), "irc", "charlie"),
+            (User(handle="", id="131", name="David"), "irc", "David"),
+            (User(handle="eve", id="415", name="Eve"), "matrix", "@eve:matrix.org"),
+            (User(handle="charlie", id="112", name="Charlie"), "mattermost", "@charlie"),
+            (User(handle="", id="131", name="David"), "mattermost", "David"),
+            (User(handle="eve", id="415", name="Eve"), "messenger", "@Eve"),
+            (User(handle="john_doe", id="123", name="John Doe"), "slack", "<@123>"),
+            (User(handle="frank", id="161", name="Frank"), "symphony", "@Frank"),
+            (User(handle="eve", id="415", name="Eve"), "teams", "<at>Eve</at>"),
+            (User(handle="alice", id="789", name="Alice"), "telegram", "@alice"),
+            (User(handle="", id="101", name="Bob"), "telegram", "Bob"),
+            (User(handle="grace", id="718", name="Grace"), "whatsapp", "@Grace"),
+            (User(handle="heidi", id="192", name="Heidi"), "zulip", "@**Heidi**"),
+            (User(handle="ivan", id="202", name="Ivan"), "unknown", "Ivan"),
+        ],
+    )
+    def test_mention(self, user, backend, expected):
+        result = mention_user(user, backend)
+        assert result == expected
diff --git a/chatom/user.py b/chatom/user.py
index 2cfd110..4f3d102 100644
--- a/chatom/user.py
+++ b/chatom/user.py
@@ -4,7 +4,7 @@
 
 
 class User(BaseModel):
-    user: str = Field(
+    handle: str = Field(
         description="The username of the author of the message.",
     )
     email: str = Field(
@@ -15,3 +15,7 @@ class User(BaseModel):
         default="",
         description="uid of the author, for mentions",
     )
+    name: str = Field(
+        default="",
+        description="The display name of the author of the message.",
+    )
diff --git a/pyproject.toml b/pyproject.toml
index 76f6bab..bd5b37a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -9,7 +9,7 @@ description = "Minimum viable chat components"
 readme = "README.md"
 license = { text = "Apache-2.0" }
 version = "0.1.0"
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 keywords = [
     "chat",
     "chatbot",
@@ -27,7 +27,6 @@ classifiers = [
     "Programming Language :: Python :: Implementation :: CPython",
     "Programming Language :: Python :: Implementation :: PyPy",
     "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",