Sending your campaign at the right time can make all the difference. With Optimized Sending, Mailercloud automatically delivers your email to each contact at the hour they are most likely to open and engage — instead of blasting everyone at the same fixed time.
Whether you have a small list or a large audience, Optimized Sending takes the guesswork out of scheduling and helps your campaigns perform better.
When you select Optimized Sending in the "When to send" step, Mailercloud analyses each contact's past engagement history to identify the hour of the day they usually open emails. Your campaign is then delivered contact by contact — each at their personal best hour.
Here's what happens step by step:
You choose a start time. From that point, Mailercloud opens a 24-hour optimization window.
Each contact is placed into the hour they are most likely to open, based on their engagement history.
The campaign goes out hour by hour across the window — only the contacts whose best time falls in that hour are sent at that time.
You can preview the distribution on the setup screen: the "Your audience's engagement by hour" chart shows how many of your contacts fall into each hour.
The result: higher open and click rates, because emails arrive when people are actually checking their inbox — without you having to guess.
Log in to your Mailercloud account.
Create or open a campaign and proceed to the "When to send" step.
Select Optimized Sending from the sending options.
Choose your preferred start time — this is when the 24-hour window begins.
Review the "Your audience's engagement by hour" chart to see how your contacts are distributed across the window.
Click Continue to proceed and publish your campaign.
Optimized Sending relies on past open and engagement data for your contacts. A contact gets a personalised best hour only once Mailercloud has seen enough of their opens to detect a reliable pattern.
Contacts with engagement history → sent at their personalised best hour.
New contacts, or contacts with little or no open history → sent at the start of the window, just like a standard send.
Note: If your account is brand new or has sent very few campaigns, there may not be enough history yet, and the engagement chart may show little or no data. As you keep sending and contacts keep engaging, coverage improves over time.
They are not skipped or dropped. Any contact Mailercloud doesn't have a confident best hour for is delivered at the start of the window — the time you chose — exactly like a normal send. So every recipient still receives your campaign; contacts with history simply get the added benefit of best-hour timing.
Spread over 24 hours — Because the send is distributed across a full day, your campaign completes over the window rather than all at once. This is normal and is what produces the engagement lift.
Best for re-engagement and regular sends — Optimized Sending works best where you have an established, engaged audience with sending history.
Plan requirement — Optimized Sending is available on paid plans only. It is not available on the Free plan.
Time zone — The best hours and the engagement chart are shown in your account's time zone.
Why is my engagement chart empty or showing very little data? Mailercloud doesn't have enough open history for this audience yet. Keep sending engaging campaigns and coverage will build over time.
Can I still choose a start time? Yes — you pick when the 24-hour optimization window begins. Mailercloud handles the rest automatically.
How is each contact's best hour decided? It's based on each contact's historical open behaviour. The more a contact engages with your campaigns, the more confident and accurate their best hour becomes.
If you have questions or need assistance at any point, don't hesitate to reach out to our support team — we're here to help.
Happy emailing! 🚀
