diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 000000000..050501d90
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "pkg/validator/data/disposable-email-domains"]
+	path = pkg/validator/data/disposable-email-domains
+	url = git@github.com:disposable-email-domains/disposable-email-domains.git
diff --git a/pkg/trust/trust_center_access_service.go b/pkg/trust/trust_center_access_service.go
index ddf55d7d1..e3ca66eef 100644
--- a/pkg/trust/trust_center_access_service.go
+++ b/pkg/trust/trust_center_access_service.go
@@ -31,6 +31,7 @@ import (
 	"go.probo.inc/probo/pkg/gid"
 	"go.probo.inc/probo/pkg/probo"
 	"go.probo.inc/probo/pkg/statelesstoken"
+	"go.probo.inc/probo/pkg/validator"
 )
 
 type (
@@ -54,6 +55,14 @@ const (
 	TrustCenterAccessURLFormat = "https://%s/organizations/%s/trust-center/access"
 )
 
+func (tcar *TrustCenterAccessRequest) Validate() error {
+	v := validator.New()
+
+	v.Check(tcar.Email, "email", validator.NotOneOfSlice([]string{}))
+
+	return nil
+}
+
 func (s TrustCenterAccessService) ValidateToken(
 	ctx context.Context,
 	trustCenterID gid.GID,
diff --git a/pkg/validator/data/disposable-email-domains b/pkg/validator/data/disposable-email-domains
new file mode 160000
index 000000000..e38ace196
--- /dev/null
+++ b/pkg/validator/data/disposable-email-domains
@@ -0,0 +1 @@
+Subproject commit e38ace196d9d5b99ebd8c386f0f06ebe0b0b5c8a
diff --git a/pkg/validator/validator_email.go b/pkg/validator/validator_email.go
new file mode 100644
index 000000000..47f2da9cc
--- /dev/null
+++ b/pkg/validator/validator_email.go
@@ -0,0 +1 @@
+package validator
diff --git a/pkg/validator/validator_string.go b/pkg/validator/validator_string.go
index ccc6d7d70..b9b4fc339 100644
--- a/pkg/validator/validator_string.go
+++ b/pkg/validator/validator_string.go
@@ -225,6 +225,25 @@ func OneOfSlice[T any](allowed []T) ValidatorFunc {
 	}
 }
 
+// NotOneOfSlice validates that a value is not one of the values in the slice.
+// Accepts a slice of any type. Compares by value first, then by string representation.
+func NotOneOfSlice[T any](disallowed []T) ValidatorFunc {
+	oneOfSlice := OneOfSlice(disallowed)
+
+	return func(value any) *ValidationError {
+		err := oneOfSlice(disallowed)
+
+		if err == nil {
+			return newValidationError(
+				ErrorCodeInvalidEnum,
+				"must not be one of the disallowed values",
+			)
+		}
+
+		return nil
+	}
+}
+
 // OneOf validates that a value is one of the allowed values.
 // Accepts strings or types that implement fmt.Stringer as variadic arguments.
 func OneOf(allowed ...any) ValidatorFunc {