diff --git a/backend/src/server/routes/v1/invite-org-router.ts b/backend/src/server/routes/v1/invite-org-router.ts
index 117532703..525d51913 100644
--- a/backend/src/server/routes/v1/invite-org-router.ts
+++ b/backend/src/server/routes/v1/invite-org-router.ts
@@ -82,7 +82,8 @@ export const registerInviteOrgRouter = async (server: FastifyZodProvider) => {
     url: "/signup-resend",
     config: {
       rateLimit: smtpRateLimit({
-        keyGenerator: (req) => (req.body as { membershipId: string }).membershipId
+        keyGenerator: (req) =>
+          (req.body as { membershipId?: string })?.membershipId?.trim().substring(0, 100) ?? req.realIp
       })
     },
     method: "POST",
diff --git a/backend/src/server/routes/v1/password-router.ts b/backend/src/server/routes/v1/password-router.ts
index 32921087b..eeb730f29 100644
--- a/backend/src/server/routes/v1/password-router.ts
+++ b/backend/src/server/routes/v1/password-router.ts
@@ -81,7 +81,7 @@ export const registerPasswordRouter = async (server: FastifyZodProvider) => {
     url: "/email/password-reset",
     config: {
       rateLimit: smtpRateLimit({
-        keyGenerator: (req) => (req.body as { email: string }).email
+        keyGenerator: (req) => (req.body as { email?: string })?.email?.trim().substring(0, 100) ?? req.realIp
       })
     },
     schema: {
diff --git a/backend/src/server/routes/v2/user-router.ts b/backend/src/server/routes/v2/user-router.ts
index 730d34bb9..bbd566334 100644
--- a/backend/src/server/routes/v2/user-router.ts
+++ b/backend/src/server/routes/v2/user-router.ts
@@ -13,7 +13,7 @@ export const registerUserRouter = async (server: FastifyZodProvider) => {
     url: "/me/emails/code",
     config: {
       rateLimit: smtpRateLimit({
-        keyGenerator: (req) => (req.body as { username: string }).username
+        keyGenerator: (req) => (req.body as { username?: string })?.username?.trim().substring(0, 100) ?? req.realIp
       })
     },
     schema: {
diff --git a/backend/src/server/routes/v3/signup-router.ts b/backend/src/server/routes/v3/signup-router.ts
index 275836b1e..c249e7dbe 100644
--- a/backend/src/server/routes/v3/signup-router.ts
+++ b/backend/src/server/routes/v3/signup-router.ts
@@ -14,7 +14,7 @@ export const registerSignupRouter = async (server: FastifyZodProvider) => {
     method: "POST",
     config: {
       rateLimit: smtpRateLimit({
-        keyGenerator: (req) => (req.body as { email: string }).email
+        keyGenerator: (req) => (req.body as { email?: string })?.email?.trim().substring(0, 100) ?? req.realIp
       })
     },
     schema: {