diff --git a/API/ROLAC.API/Services/Notifications/NotificationModels.cs b/API/ROLAC.API/Services/Notifications/NotificationModels.cs
new file mode 100644
index 0000000..3e14f3d
--- /dev/null
+++ b/API/ROLAC.API/Services/Notifications/NotificationModels.cs
@@ -0,0 +1,49 @@
+namespace ROLAC.API.Services.Notifications;
+
+/// <summary>Canonical channel discriminators stored in NotificationLog.Channel.</summary>
+public static class NotificationChannels
+{
+    public const string Email = "email";
+    public const string Line  = "line";
+}
+
+/// <summary>Canonical target-type discriminators stored in NotificationLog.TargetType.</summary>
+public static class NotificationTargetTypes
+{
+    public const string Email = "email";
+    public const string User  = "user";
+    public const string Group = "group";
+}
+
+/// <summary>Canonical send statuses stored in NotificationLog.Status.</summary>
+public static class NotificationStatuses
+{
+    public const string Sent   = "sent";
+    public const string Failed = "failed";
+}
+
+/// <summary>One failed delivery within a send batch.</summary>
+public sealed record NotificationFailure(string Target, string Error);
+
+/// <summary>Aggregated outcome of a send call.</summary>
+public sealed record NotificationResult(
+    int SentCount, int FailedCount, IReadOnlyList<NotificationFailure> Failures)
+{
+    public static NotificationResult Empty { get; } =
+        new(0, 0, Array.Empty<NotificationFailure>());
+}
+
+/// <summary>A file attached to an outbound email.</summary>
+public sealed record EmailAttachment(string FileName, string ContentType, byte[] Content);
+
+/// <summary>
+/// A request to send one email to a set of members (resolved via Member.Email) and/or raw
+/// addresses. The caller supplies the final HTML body — no templating in this phase.
+/// </summary>
+public sealed record EmailMessage(
+    IReadOnlyList<int>    MemberIds,
+    IReadOnlyList<string> Addresses,
+    string                Subject,
+    string                HtmlBody,
+    IReadOnlyList<EmailAttachment>? Attachments = null,
+    string?               SentByUserId = null);