Typically, a confirmation email from Booking.com is sent almost instantaneously, usually arriving in your inbox within two to five minutes of completing the reservation process. This automated system is designed to provide immediate peace of mind for travelers. However, there are several factors that can cause a delay. If the property is a "request-based" booking where the host needs to manually approve your stay, it could take up to 24 hours to receive the final confirmation. Additionally, during peak holiday seasons or major technical outages, the delivery might be slowed by high server traffic. If you haven't received your email within ten minutes, the first step is always to check your "Spam" or "Promotions" folder, as aggressive filters often flag travel confirmation emails. You can also log into your Booking.com account directly; if the reservation appears in the "Bookings" section of your profile, it is confirmed even if the email is lagging. If the booking isn't in your account and no email has arrived after an hour, it is possible that the transaction failed or there was a typo in the email address provided during the guest checkout process.