diff --git a/source/api/actions/member_info.ts b/source/api/actions/member_info.ts
index 9fa3b5e..cf8a133 100644
--- a/source/api/actions/member_info.ts
+++ b/source/api/actions/member_info.ts
@@ -32,7 +32,7 @@ namespace _espe.api
 					name_real_value : string;
 					name_real_index : int;
 					name_login : string;
-					email_address_veiled : string;
+					email_address_veiled : (null | string);
 					email_address_nominal : string;
 				}
 			)
@@ -65,7 +65,7 @@ namespace _espe.api
 						},
 						"email_address_veiled": {
 							"type": "string",
-							"nullable": false,
+							"nullable": true,
 						},
 						"email_address_nominal": {
 							"type": "string",
@@ -100,7 +100,7 @@ namespace _espe.api
 							name_real_value : string;
 							name_real_index : int;
 							name_login : string;
-							email_address_veiled : string;
+							email_address_veiled : (null | string);
 							email_address_nominal : string;
 						}
 					) = await _espe.service.member.info(member_id);
diff --git a/source/api/actions/member_project.ts b/source/api/actions/member_project.ts
index f188cec..21cc165 100644
--- a/source/api/actions/member_project.ts
+++ b/source/api/actions/member_project.ts
@@ -75,7 +75,15 @@ namespace _espe.api
 							{
 								"membership_number": input.membership_number,
 								"name_real_value": input.name_real_value,
-								"email_address_private": (input.email_address_private ?? null),
+								"email_address_private": (
+									("email_address_private" in input)
+									? (
+										(input.email_address_private !== "")
+										? input.email_address_private
+										: null
+									)
+									: null
+								),
 							}
 						);
 						return Promise.resolve({
diff --git a/source/api/actions/member_read.ts b/source/api/actions/member_read.ts
index 9d9bbe6..90de074 100644
--- a/source/api/actions/member_read.ts
+++ b/source/api/actions/member_read.ts
@@ -25,7 +25,7 @@ namespace _espe.api
 		register<
 			null,
 			{
-				membership_number : string;
+				membership_number : (null | string);
 				name_real_value : string;
 				name_real_index : int;
 				email_address_private : (null | string);
@@ -36,7 +36,7 @@ namespace _espe.api
 				email_redirect_to_private_address : boolean;
 				email_allow_sending : boolean;
 				password_set : boolean;
-				email_address_veiled : string;
+				email_address_veiled : (null | string);
 				email_address_nominal : string;
 				name_login : string;
 			}
@@ -51,7 +51,7 @@ namespace _espe.api
 					"type": "object",
 					"properties": {
 						"membership_number": {
-							"nullable": false,
+							"nullable": true,
 							"type": "string"
 						},
 						"name_real_value": {
@@ -95,7 +95,7 @@ namespace _espe.api
 							"type": "boolean"
 						},
 						"email_address_veiled": {
-							"nullable": false,
+							"nullable": true,
 							"type": "string"
 						},
 						"email_address_nominal": {
diff --git a/source/database.ts b/source/database.ts
index ee68858..433b374 100644
--- a/source/database.ts
+++ b/source/database.ts
@@ -19,7 +19,7 @@ namespace _espe.database
 	/**
 	 */
 	const _compatible_revisions : Array<string> = [
-		"r3",
+		"r4",
 	];
 	
 		
diff --git a/source/services/member.ts b/source/services/member.ts
index 9c5bec1..bcb513f 100644
--- a/source/services/member.ts
+++ b/source/services/member.ts
@@ -180,15 +180,19 @@ namespace _espe.service.member
 	 */
 	export function email_address_veiled(
 		object : _espe.type.member_object
-	) : string
+	) : (null | string)
 	{
-		return lib_plankton.string.coin(
-			"{{prefix}}{{membership_number}}@{{domain}}",
-			{
-				"prefix": _espe.conf.get().settings.prefix_for_nominal_email_addresses,
-				"membership_number": object.membership_number,
-				"domain": _espe.conf.get().settings.target_domain,
-			}
+		return (
+			(object.membership_number === null)
+			? null
+			: lib_plankton.string.coin(
+				"{{prefix}}{{membership_number}}@{{domain}}",
+				{
+					"prefix": _espe.conf.get().settings.prefix_for_nominal_email_addresses,
+					"membership_number": object.membership_number,
+					"domain": _espe.conf.get().settings.target_domain,
+				}
+			)
 		);
 	}
 	
@@ -385,7 +389,7 @@ namespace _espe.service.member
 				name_real_value : string;
 				name_real_index : int;
 				name_login : string;
-				email_address_veiled : string;
+				email_address_veiled : (null | string);
 				email_address_nominal : string;
 			}
 		)
diff --git a/source/types.ts b/source/types.ts
index 405013c..3929d8c 100644
--- a/source/types.ts
+++ b/source/types.ts
@@ -24,7 +24,7 @@ namespace _espe.type
 	/**
 	 */
 	export type member_object = {
-		membership_number : string;
+		membership_number : (null | string);
 		name_real_value : string;
 		name_real_index : int;
 		email_address_private : (null | string);