diff --git a/packages/services/src/invitation/__tests__/invitation.test.ts b/packages/services/src/invitation/__tests__/invitation.test.ts
index 02127565a..8dcbe71a4 100644
--- a/packages/services/src/invitation/__tests__/invitation.test.ts
+++ b/packages/services/src/invitation/__tests__/invitation.test.ts
@@ -74,6 +74,18 @@ describe("createInvitation", () => {
     });
   });
 
+  test("stores the email trimmed and lowercased", async () => {
+    await withTestTransaction(async (tx) => {
+      const email = `${TEST_PREFIX}-case-${Date.now()}@example.com`;
+      const row = await createInvitation({
+        ctx: { ...teamCtx, db: tx },
+        input: { email: `  ${email.toUpperCase()} ` },
+      });
+
+      expect(row.email).toBe(email);
+    });
+  });
+
   test("rejects read-only actor", async () => {
     await withTestTransaction(async (tx) => {
       const readOnlyCtx = {
@@ -146,6 +158,39 @@ describe("getInvitationByToken", () => {
     });
   });
 
+  test("matches a legacy mixed-case invitation case-insensitively", async () => {
+    await withTestTransaction(async (tx) => {
+      const ctx = { ...teamCtx, db: tx };
+      const email = `${TEST_PREFIX}-legacy-${Date.now()}@example.com`;
+      const token = crypto.randomUUID();
+      const legacy = await tx
+        .insert(invitation)
+        .values({
+          email: email.toUpperCase(),
+          workspaceId: teamCtx.workspace.id,
+          token,
+          expiresAt: new Date(Date.now() + 60_000),
+        })
+        .returning()
+        .get();
+
+      const row = await getInvitationByToken({
+        ctx,
+        input: { token, email },
+      });
+      expect(row.id).toBe(legacy.id);
+
+      const workspaceRow = await acceptInvitation({
+        ctx: {
+          ...makeUserCtx(teamCtx.workspace, { userId: acceptingUserId }),
+          db: tx,
+        },
+        input: { id: legacy.id, email },
+      });
+      expect(workspaceRow.id).toBe(teamCtx.workspace.id);
+    });
+  });
+
   test("rejects a valid token for the wrong email", async () => {
     await withTestTransaction(async (tx) => {
       const ctx = { ...teamCtx, db: tx };
diff --git a/packages/services/src/invitation/accept.ts b/packages/services/src/invitation/accept.ts
index d8f7c0aad..ea7e4c158 100644
--- a/packages/services/src/invitation/accept.ts
+++ b/packages/services/src/invitation/accept.ts
@@ -1,4 +1,4 @@
-import { and, eq, gte, isNull } from "@openstatus/db";
+import { and, eq, gte, isNull, sql } from "@openstatus/db";
 import {
   invitation,
   selectWorkspaceSchema,
@@ -58,7 +58,8 @@ export async function acceptInvitation(args: {
     const existing = await tx.query.invitation.findFirst({
       where: and(
         eq(invitation.id, input.id),
-        eq(invitation.email, input.email),
+        // Rows created before emails were normalized keep their original casing.
+        sql`lower(${invitation.email}) = ${input.email}`,
         isNull(invitation.acceptedAt),
         gte(invitation.expiresAt, new Date()),
       ),
diff --git a/packages/services/src/invitation/list.ts b/packages/services/src/invitation/list.ts
index ae607b670..3c1ed2514 100644
--- a/packages/services/src/invitation/list.ts
+++ b/packages/services/src/invitation/list.ts
@@ -1,4 +1,4 @@
-import { and, db as defaultDb, eq, gte, isNull } from "@openstatus/db";
+import { and, db as defaultDb, eq, gte, isNull, sql } from "@openstatus/db";
 import {
   invitation,
   selectInvitationSchema,
@@ -59,7 +59,8 @@ export async function getInvitationByToken(args: {
       eq(invitation.token, input.token),
       isNull(invitation.acceptedAt),
       gte(invitation.expiresAt, new Date()),
-      eq(invitation.email, input.email),
+      // Rows created before emails were normalized keep their original casing.
+      sql`lower(${invitation.email}) = ${input.email}`,
     ),
     with: { workspace: true },
   });
diff --git a/packages/services/src/invitation/schemas.ts b/packages/services/src/invitation/schemas.ts
index 85dac2ef0..bd163ebcc 100644
--- a/packages/services/src/invitation/schemas.ts
+++ b/packages/services/src/invitation/schemas.ts
@@ -1,7 +1,13 @@
 import { z } from "zod";
 
+/**
+ * Invitation emails are stored and compared lowercase. Trim + lowercase run
+ * before the format check so `" Foo@Bar.com "` normalizes instead of failing.
+ */
+const InvitationEmail = z.string().trim().toLowerCase().pipe(z.email());
+
 export const CreateInvitationInput = z.object({
-  email: z.email(),
+  email: InvitationEmail,
 });
 export type CreateInvitationInput = z.infer<typeof CreateInvitationInput>;
 
@@ -13,7 +19,7 @@ export type ListInvitationsInput = z.infer<typeof ListInvitationsInput>;
 
 export const GetInvitationByTokenInput = z.object({
   token: z.string().min(1),
-  email: z.email(),
+  email: InvitationEmail,
 });
 export type GetInvitationByTokenInput = z.infer<
   typeof GetInvitationByTokenInput
@@ -21,6 +27,6 @@ export type GetInvitationByTokenInput = z.infer<
 
 export const AcceptInvitationInput = z.object({
   id: z.number().int(),
-  email: z.email(),
+  email: InvitationEmail,
 });
 export type AcceptInvitationInput = z.infer<typeof AcceptInvitationInput>;