diff --git a/source/conf.ts b/source/conf.ts
index cd440d7..f492559 100644
--- a/source/conf.ts
+++ b/source/conf.ts
@@ -24,6 +24,24 @@ along with »munin«. If not, see <http://www.gnu.org/licenses/>.
 namespace _munin.conf
 {
 	
+	/**
+	 */
+	type type_reminder_raw = {
+		frequency : (
+			"hourly"
+			|
+			"daily"
+			|
+			"weekly"
+			|
+			"monthly"
+		);
+		offset : int;
+		from : int;
+		to : int;
+	};
+	
+	
 	/**
 	 */
 	type type_conf_v1 = {
@@ -236,7 +254,71 @@ namespace _munin.conf
 	
 	/**
 	 */
-	export type type_conf = type_conf_v4;
+	type type_conf_v5 = {
+		sources : Array<
+			(
+				{
+					kind : "ical_feed";
+					data : {
+						url : string;
+						filtration : {
+							category_whitelist : (null | Array<string>);
+							category_blacklist : (null | Array<string>);
+							title_whitelist : (null | Array<string>);
+							title_blacklist : (null | Array<string>);
+						}
+					}
+				}
+			)
+		>;
+		targets : Array<
+			(
+				{
+					kind : "email";
+					data : {
+						smtp_host : string;
+						smtp_port : int;
+						smtp_username : string;
+						smtp_password : string;
+						sender : string;
+						receivers : Array<string>;
+						hide_tags : boolean;
+						/**
+						 * in hours
+						 */
+						reminders : Array<type_reminder_raw>;
+					}
+				}
+				|
+				{
+					kind : "telegram_bot";
+					data : {
+						bot_token : string;
+						chat_id : int;
+						hide_tags : boolean;
+						/**
+						 * in hours
+						 */
+						reminders : Array<type_reminder_raw>;
+					}
+				}
+			)
+		>;
+		settings : {
+			interval : float;
+		};
+		labels : {
+			head : string;
+			title : string;
+			time : string;
+			location : string;
+		};
+	};
+	
+	
+	/**
+	 */
+	export type type_conf = type_conf_v5;
 	
 	
 	/**
@@ -396,6 +478,65 @@ namespace _munin.conf
 	}
 	
 	
+	/**
+	 */
+	function convert_from_v4(
+		conf_v4 : type_conf_v4
+	) : type_conf_v5
+	{
+		const map_reminder = hours => ({
+			"frequency": "hourly",
+			"offset": 0,
+			"from": hours,
+			"to": (hours + 1),
+		} as type_reminder_raw);
+		return {
+			"sources": conf_v4.sources,
+			"targets": conf_v4.targets.map(
+				target => {
+					switch (target.kind) {
+						case "email": {
+							return {
+								"kind": "email",
+								"data": {
+									"smtp_host": target.data.smtp_host,
+									"smtp_port": target.data.smtp_port,
+									"smtp_username": target.data.smtp_username,
+									"smtp_password": target.data.smtp_password,
+									"sender": target.data.sender,
+									"receivers": target.data.receivers,
+									"hide_tags": target.data.hide_tags,
+									"reminders": target.data.reminders.map(map_reminder),
+								},
+							};
+							break;
+						}
+						case "telegram_bot": {
+							return {
+								"kind": "telegram_bot",
+								"data": {
+									"bot_token": target.data.bot_token,
+									"chat_id": target.data.chat_id,
+									"hide_tags": target.data.hide_tags,
+									"reminders": target.data.reminders.map(map_reminder),
+								},
+							};
+							break;
+						}
+						default: {
+							// return target;
+							throw (new Error("unhandled target kind: " + String(target)));
+							break;
+						}
+					}
+				}
+			),
+			"settings": conf_v4.settings,
+			"labels": conf_v4.labels,
+		};
+	}
+	
+	
 	/**
 	 */
 	function schema_source_kalender_digital(
@@ -546,6 +687,136 @@ namespace _munin.conf
 	}
 	
 	
+	/**
+	 */
+	function schema_sources(
+		version : string
+	) : lib_plankton.conf.type_schema
+	{
+		switch (version) {
+			case "1": {
+				return {
+					"nullable": false,
+					"type": "array",
+					"items": {
+						"nullable": false,
+						"anyOf": [
+							schema_source_kalender_digital(version),
+						],
+					}
+				};
+				break;
+			}
+			default:
+			case "2": {
+				return {
+					"nullable": false,
+					"type": "array",
+					"items": {
+						"nullable": false,
+						"anyOf": [
+							schema_source_ical_feed(version),
+						],
+					}
+				};
+				break;
+			}
+		}
+	}
+	
+	
+	/**
+	 */
+	function schema_reminder(
+		version : string
+	) : lib_plankton.conf.type_schema
+	{
+		switch (version)
+		{
+			case "1":
+			case "2":
+			case "3":
+			case "4":
+			{
+				return {
+					"type": "integer",
+				};
+			}
+			case "5":
+			default:
+			{
+				return {
+					"nullable": false,
+					"type": "object",
+					"properties": {
+						"frequency": {
+							"nullable": false,
+							"type": "string",
+							"enum": [
+								"hourly",
+								"daily",
+								"weekly",
+								"monthly",
+							]
+						},
+						"offset": {
+							"nullable": false,
+							"type": "integer",
+							"default": 0
+						},
+						"from": {
+							"nullable": false,
+							"type": "integer"
+						},
+						"to": {
+							"nullable": false,
+							"type": "integer"
+						},
+					},
+					"additionalProperties": false,
+					"required": [
+						"frequency",
+						"from",
+						"to",
+					]
+				};
+				break;
+			}
+		}
+	}
+
+	
+	/**
+	 */
+	function default_reminder(
+		version : string
+	) : any
+	{
+		switch (version)
+		{
+			case "1":
+			case "2":
+			case "3":
+			case "4":
+			{
+				return [24];
+			}
+			case "5":
+			default:
+			{
+				return [
+					{
+						"frequency": "hourly",
+						"from": 24,
+						"to": 25
+					}
+				];
+				break;
+			}
+		}
+	}
+		
+	
 	/**
 	 */
 	function schema_target_email(
@@ -602,11 +873,8 @@ namespace _munin.conf
 						"reminders": {
 							"nullable": false,
 							"type": "array",
-							"items": {
-								"nullable": false,
-								"type": "integer"
-							},
-							"default": [24.0],
+							"items": schema_reminder(version),
+							"default": default_reminder(version),
 						},
 					},
 					"additionalProperties": false,
@@ -628,44 +896,6 @@ namespace _munin.conf
 	}
 	
 	
-	/**
-	 */
-	function schema_sources(
-		version : string
-	) : lib_plankton.conf.type_schema
-	{
-		switch (version) {
-			case "1": {
-				return {
-					"nullable": false,
-					"type": "array",
-					"items": {
-						"nullable": false,
-						"anyOf": [
-							schema_source_kalender_digital(version),
-						],
-					}
-				};
-				break;
-			}
-			default:
-			case "2": {
-				return {
-					"nullable": false,
-					"type": "array",
-					"items": {
-						"nullable": false,
-						"anyOf": [
-							schema_source_ical_feed(version),
-						],
-					}
-				};
-				break;
-			}
-		}
-	}
-	
-	
 	/**
 	 */
 	function schema_target_telegram_bot(
@@ -701,11 +931,8 @@ namespace _munin.conf
 						"reminders": {
 							"nullable": false,
 							"type": "array",
-							"items": {
-								"nullable": false,
-								"type": "integer"
-							},
-							"default": [24.0],
+							"items": schema_reminder(version),
+							"default": default_reminder(version),
 						},
 					},
 					"additionalProperties": false,
@@ -737,13 +964,18 @@ namespace _munin.conf
 				"nullable": false,
 				"anyOf": (() => {
 					switch (version) {
-						default: {
+						case "1":
+						case "2":
+						{
 							return [
 								schema_target_telegram_bot(version),
 							];
 							break;
 						}
-						case "3": {
+						case "4":
+						case "5":
+						default:
+						{
 							return [
 								schema_target_email(version),
 								schema_target_telegram_bot(version),
@@ -824,7 +1056,7 @@ namespace _munin.conf
 	/**
 	 */
 	export function schema(
-		version : string = "4"
+		version : string = "5"
 	) : lib_plankton.conf.type_schema
 	{
 		switch (version) {
@@ -852,7 +1084,9 @@ namespace _munin.conf
 			}
 			case "2":
 			case "3":
-			case "4": {
+			case "4":
+			case "5":
+			{
 				return {
 					"nullable": false,
 					"type": "object",
@@ -887,7 +1121,8 @@ namespace _munin.conf
 				"1": {"target": "2", "function": convert_from_v1},
 				"2": {"target": "3", "function": convert_from_v2},
 				"3": {"target": "4", "function": convert_from_v3},
-				"4": null,
+				"4": {"target": "5", "function": convert_from_v4},
+				"5": null,
 			}
 		);
 		
@@ -925,7 +1160,7 @@ namespace _munin.conf
 			}
 		}
 		 */
-		return (conf_raw.content as type_conf_v4);
+		return (conf_raw.content as type_conf_v5);
 	}
 	
 }
diff --git a/source/logic.ts b/source/logic.ts
index 693811f..a9efba2 100644
--- a/source/logic.ts
+++ b/source/logic.ts
@@ -21,45 +21,6 @@ along with »munin«. If not, see <http://www.gnu.org/licenses/>.
 namespace _munin.logic
 {
 	
-	/**
-	 * @todo Tests schreiben
-	 */
-	function shall_remind(
-		event : _munin.type_event,
-		reminder : type_reminder,
-		{
-			"pit": pit = lib_plankton.pit.now(),
-			"interval": interval = 1,
-		} : {
-			pit ?: lib_plankton.pit.type_pit;
-			interval ?: int;
-		} = {
-		}
-	) : boolean
-	{
-		const window_from : lib_plankton.pit.type_pit = lib_plankton.pit.shift_hour(
-			pit,
-			0
-		);
-		const window_to : lib_plankton.pit.type_pit = lib_plankton.pit.shift_hour(
-			pit,
-			interval
-		);
-		const event_begin : lib_plankton.pit.type_pit = lib_plankton.pit.from_datetime(
-			event.begin
-		);
-		const reminder_time : lib_plankton.pit.type_pit = lib_plankton.pit.shift_hour(
-			event_begin,
-			(-reminder)
-		);
-		return lib_plankton.pit.is_between(
-			reminder_time,
-			window_from,
-			window_to
-		);
-	}
-	
-	
 	/**
 	 */
 	function frequency_anchor(
@@ -90,7 +51,7 @@ namespace _munin.logic
 	/**
 	 */
 	export function reminder_due(
-		reminder : type_reminder_new,
+		reminder : type_reminder,
 		{
 			"pit": pit = lib_plankton.pit.now(),
 			"interval": interval = 1,
@@ -105,35 +66,46 @@ namespace _munin.logic
 			reminder.frequency,
 			{"pit": pit}
 		);
-		// 0 ≤ ((p - a(p)) - o) < i
-		const x : float = (
-			(
-				(
-					lib_plankton.pit.to_unix_timestamp(pit)
-					-
-					lib_plankton.pit.to_unix_timestamp(anchor)
-				)
-				/
-				(60 * 60)
-			)
-			-
-			reminder.offset
+		const window_from : lib_plankton.pit.type_pit = lib_plankton.pit.shift_hour(
+			anchor,
+			(reminder.offset + 0)
 		);
-		return ((0 <= x) && (x < interval));
+		const window_to : lib_plankton.pit.type_pit = lib_plankton.pit.shift_hour(
+			anchor,
+			(reminder.offset + interval)
+		);
+		const result : boolean = lib_plankton.pit.is_between(
+			pit,
+			window_from,
+			window_to
+		);
+		lib_plankton.log._info(
+			"munin.logic.reminder_due",
+			{
+				"details": {
+					"reminder": reminder,
+					"datetime": lib_plankton.pit.to_datetime(pit),
+					"interval": interval,
+					"anchor": lib_plankton.pit.to_datetime(anchor),
+					"window_from": lib_plankton.pit.to_datetime(window_from),
+					"window_to": lib_plankton.pit.to_datetime(window_to),
+					"result": result,
+				}
+			}
+		);
+		return result;
 	}
 	
 	
 	/**
 	 */
 	export function reminder_event_in_window(
-		reminder : type_reminder_new,
+		reminder : type_reminder,
 		event : _munin.type_event,
 		{
 			"pit": pit = lib_plankton.pit.now(),
-			"interval": interval = 1,
 		} : {
 			pit ?: lib_plankton.pit.type_pit;
-			interval ?: int;
 		} = {
 		}
 	) : boolean
@@ -153,41 +125,26 @@ namespace _munin.logic
 		const event_begin : lib_plankton.pit.type_pit = lib_plankton.pit.from_datetime(
 			event.begin
 		);
-		return lib_plankton.pit.is_between(
+		const result : boolean = lib_plankton.pit.is_between(
 			event_begin,
 			window_from,
 			window_to
 		);
-	}
-		
-	
-	/**
-	 */
-	function shall_remind_new(
-		reminder : type_reminder_new,
-		event : _munin.type_event,
-		{
-			"pit": pit = lib_plankton.pit.now(),
-			"interval": interval = 1,
-		} : {
-			pit ?: lib_plankton.pit.type_pit;
-			interval ?: int;
-		} = {
-		}
-	) : boolean
-	{
-		return (
-			reminder_due(
-				reminder,
-				{"pit": pit, "interval": interval}
-			)
-			&&
-			reminder_event_in_window(
-				reminder,
-				event,
-				{"pit": pit, "interval": interval}
-			)
+		lib_plankton.log._info(
+			"munin.logic.reminder_event_in_window",
+			{
+				"details": {
+					"reminder": reminder,
+					"event": event,
+					"datetime": lib_plankton.pit.to_datetime(pit),
+					"anchor": lib_plankton.pit.to_datetime(anchor),
+					"window_from": lib_plankton.pit.to_datetime(window_from),
+					"window_to": lib_plankton.pit.to_datetime(window_to),
+					"result": result,
+				}
+			}
 		);
+		return result;
 	}
 	
 		
@@ -211,17 +168,30 @@ namespace _munin.logic
 			.reduce((x, y) => x.concat(y), [])
 		);
 		for (const target of targets) {
-			for (const reminder_hours of target.reminders) {
-				for (const event of events) {
-					const remind : boolean = shall_remind(
-						event,
-						reminder_hours,
-						{
-							"pit": now,
-							"interval": conf.settings.interval,
-						}
+			for (const reminder of target.reminders) {
+				const due : boolean = reminder_due(
+					reminder,
+					{
+						"pit": now,
+						"interval": conf.settings.interval,
+					}
+				);
+				if (! due)
+				{
+					// do nothing
+				}
+				else
+				{
+					const events_matching : Array<_munin.type_event> = events.filter(
+						event => reminder_event_in_window(
+							reminder,
+							event,
+							{
+								"pit": now,
+							}
+						)
 					);
-					if (! remind) {
+					if (events_matching.length <= 0) {
 						// do nothing
 					}
 					else {
@@ -229,7 +199,7 @@ namespace _munin.logic
 							"munin.remind.do",
 							{
 								"details": {
-									"event": event,
+									"events": events,
 									"target": target.show(),
 								}
 							}
@@ -238,18 +208,24 @@ namespace _munin.logic
 							// do nothing
 						}
 						else {
-							try {
-								await target.send(conf.labels, event);
-							}
-							catch (error) {
-								lib_plankton.log.error(
-									"munin.remind.error",
-									{
-										"details": {
-											"message": String(error),
+							/**
+							 * @todo bundle?
+							 */
+							for (const event of events_matching)
+							{
+								try {
+									await target.send(conf.labels, event);
+								}
+								catch (error) {
+									lib_plankton.log.error(
+										"munin.remind.error",
+										{
+											"details": {
+												"message": String(error),
+											}
 										}
-									}
-								);
+									);
+								}
 							}
 						}
 					}
diff --git a/source/main.ts b/source/main.ts
index 9fb52fa..af737a4 100644
--- a/source/main.ts
+++ b/source/main.ts
@@ -158,8 +158,9 @@ namespace _munin
 											"data": {
 												"target": "stdout",
 												"format": {
-													"kind": "human_readable",
+													"kind": "jsonl",
 													"data": {
+														"structured": true
 													}
 												}
 											}
diff --git a/source/targets/email.ts b/source/targets/email.ts
index b9d33fa..358ebd6 100644
--- a/source/targets/email.ts
+++ b/source/targets/email.ts
@@ -31,10 +31,7 @@ namespace _munin.targets.email
 		sender : string;
 		receivers : Array<string>;
 		hide_tags : boolean;
-		/**
-		 * in hours
-		 */
-		reminders : Array<int>;
+		reminders : Array<_munin.type_reminder>;
 	};
 	
 	
diff --git a/source/targets/telegram_bot.ts b/source/targets/telegram_bot.ts
index df24da4..44f0dd7 100644
--- a/source/targets/telegram_bot.ts
+++ b/source/targets/telegram_bot.ts
@@ -27,7 +27,7 @@ namespace _munin.targets.telegram_bot
 		bot_token : string;
 		chat_id : int;
 		hide_tags : boolean;
-		reminders : Array<int>;
+		reminders : Array<_munin.type_reminder>;
 	};
 	
 	
diff --git a/source/test.ts b/source/test.ts
index 91b0842..91bed40 100644
--- a/source/test.ts
+++ b/source/test.ts
@@ -359,7 +359,6 @@ namespace _munin.test
 				},
 				{
 					"pit": datetime_to_pit(testcase.input.datetime),
-					"interval": testcase.input.interval,
 				}
 			);
 			
diff --git a/source/types.ts b/source/types.ts
index e29db21..9c56ef0 100644
--- a/source/types.ts
+++ b/source/types.ts
@@ -67,15 +67,8 @@ namespace _munin
 	
 	/**
 	 * @todo rename
-	 * @todo extend
 	 */
-	export type type_reminder = int;
-	
-	
-	/**
-	 * @todo rename
-	 */
-	export type type_reminder_new = {
+	export type type_reminder = {
 		frequency : enum_frequency;
 		offset : int;
 		from : int;