diff --git a/.env.example b/.env.example
index 99636771a9..a00064207f 100644
--- a/.env.example
+++ b/.env.example
@@ -32,3 +32,5 @@ EMAIL_SERVER_PORT=587
 EMAIL_SERVER_USER='<office365_emailAddress>'
 # Keep in mind that if you have 2FA enabled, you will need to provision an App Password.
 EMAIL_SERVER_PASSWORD='<office365_password>'
+# ApiKey for cronjobs
+CRON_API_KEY='0cc0e6c35519bba620c9360cfe3e68d0'
diff --git a/lib/emails/EventOrganizerRequestReminderMail.ts b/lib/emails/EventOrganizerRequestReminderMail.ts
new file mode 100644
index 0000000000..1f935943d2
--- /dev/null
+++ b/lib/emails/EventOrganizerRequestReminderMail.ts
@@ -0,0 +1,25 @@
+import dayjs, { Dayjs } from "dayjs";
+
+import utc from "dayjs/plugin/utc";
+import timezone from "dayjs/plugin/timezone";
+import toArray from "dayjs/plugin/toArray";
+import localizedFormat from "dayjs/plugin/localizedFormat";
+import EventOrganizerRequestMail from "@lib/emails/EventOrganizerRequestMail";
+
+dayjs.extend(utc);
+dayjs.extend(timezone);
+dayjs.extend(toArray);
+dayjs.extend(localizedFormat);
+
+export default class EventOrganizerRequestReminderMail extends EventOrganizerRequestMail {
+  protected getBodyHeader(): string {
+    return "An event is still waiting for your approval.";
+  }
+
+  protected getSubject(): string {
+    const organizerStart: Dayjs = <Dayjs>dayjs(this.calEvent.startTime).tz(this.calEvent.organizer.timeZone);
+    return `Event request is still waiting: ${this.calEvent.attendees[0].name} - ${organizerStart.format(
+      "LT dddd, LL"
+    )} - ${this.calEvent.type}`;
+  }
+}
diff --git a/pages/api/cron/bookingReminder.ts b/pages/api/cron/bookingReminder.ts
new file mode 100644
index 0000000000..1bf9da47e0
--- /dev/null
+++ b/pages/api/cron/bookingReminder.ts
@@ -0,0 +1,74 @@
+import type { NextApiRequest, NextApiResponse } from "next";
+import prisma from "@lib/prisma";
+import dayjs from "dayjs";
+import { ReminderType } from "@prisma/client";
+import EventOrganizerRequestReminderMail from "@lib/emails/EventOrganizerRequestReminderMail";
+import { CalendarEvent } from "@lib/calendarClient";
+
+export default async function handler(req: NextApiRequest, res: NextApiResponse) {
+  const apiKey = req.query.apiKey;
+  if (process.env.CRON_API_KEY != apiKey) {
+    return res.status(401).json({ message: "Not authenticated" });
+  }
+
+  if (req.method == "POST") {
+    const reminderIntervalMinutes = [48 * 60, 24 * 60, 3 * 60];
+    let notificationsSent = 0;
+    for (const interval of reminderIntervalMinutes) {
+      const bookings = await prisma.booking.findMany({
+        where: {
+          confirmed: false,
+          rejected: false,
+          createdAt: {
+            lte: dayjs().add(-interval, "minutes").toDate(),
+          },
+        },
+        select: {
+          title: true,
+          description: true,
+          startTime: true,
+          endTime: true,
+          attendees: true,
+          user: true,
+          id: true,
+          uid: true,
+        },
+      });
+
+      const reminders = await prisma.reminderMail.findMany({
+        where: {
+          reminderType: ReminderType.PENDING_BOOKING_CONFIRMATION,
+          referenceId: {
+            in: bookings.map((b) => b.id),
+          },
+          elapsedMinutes: {
+            gte: interval,
+          },
+        },
+      });
+
+      for (const booking of bookings.filter((b) => !reminders.some((r) => r.referenceId == b.id))) {
+        const evt: CalendarEvent = {
+          type: booking.title,
+          title: booking.title,
+          description: booking.description,
+          startTime: booking.startTime.toISOString(),
+          endTime: booking.endTime.toISOString(),
+          organizer: { email: booking.user.email, name: booking.user.name, timeZone: booking.user.timeZone },
+          attendees: booking.attendees,
+        };
+
+        await new EventOrganizerRequestReminderMail(evt, booking.uid).sendEmail();
+        await prisma.reminderMail.create({
+          data: {
+            referenceId: booking.id,
+            reminderType: ReminderType.PENDING_BOOKING_CONFIRMATION,
+            elapsedMinutes: interval,
+          },
+        });
+        notificationsSent++;
+      }
+    }
+    res.status(200).json({ notificationsSent });
+  }
+}
diff --git a/prisma/migrations/20210718184017_reminder_mails/migration.sql b/prisma/migrations/20210718184017_reminder_mails/migration.sql
new file mode 100644
index 0000000000..7386d848ac
--- /dev/null
+++ b/prisma/migrations/20210718184017_reminder_mails/migration.sql
@@ -0,0 +1,13 @@
+-- CreateEnum
+CREATE TYPE "ReminderType" AS ENUM ('PENDING_BOOKING_CONFIRMATION');
+
+-- CreateTable
+CREATE TABLE "ReminderMail" (
+    "id" SERIAL NOT NULL,
+    "referenceId" INTEGER NOT NULL,
+    "reminderType" "ReminderType" NOT NULL,
+    "elapsedMinutes" INTEGER NOT NULL,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    PRIMARY KEY ("id")
+);
diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index 5cc676d1aa..83aed7249a 100644
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -176,3 +176,15 @@ model ResetPasswordRequest {
   email      String
   expires    DateTime
 }
+
+enum ReminderType {
+  PENDING_BOOKING_CONFIRMATION
+}
+
+model ReminderMail {
+  id             Int      @id @default(autoincrement())
+  referenceId    Int
+  reminderType   ReminderType
+  elapsedMinutes Int
+  createdAt      DateTime @default(now())
+}