Delayed delivery won’t send unless Outlook is running. Here’s the workaround.

As the saying goes, “Technology is wonderful (when it works).”

The concept of sending a delayed email is brilliant. The rules and logistics behind the concept? Notsomuch. 

Last week, I was on vacation with my family. Before I left, I scheduled an email to be sent on Thursday (while I was away) to attendees of an event we are hosting later this month. When I returned to the office the following Monday, I was dissapointed to find out that my scheduled email was not sent at the scheduled date and time.

Why? Because Outlook was not open at the time the email was scheduled to be sent. If you’re reading this, chances are you’ve found yourself in a similar situation.

When Outlook is in Cached Exchange Mode, it uses a local offline folder file (.ost) that syncs with the server periodically. If you enable the “Do not deliver before” option to delay an email, the message is stored in the local Outbox, not on the server. This means the email will only be sent if Outlook is running at the scheduled delivery time.

Luckily, we’ve found a workaround that will send delayed emails without having Outlook open.

How to Delay Email Delivery in Microsoft Outlook without having Outlook Open

Outlook typically sets Exchange accounts to Cached Mode by default. To switch to Online Mode:

Go to File → Account Settings → Account Settings.
Under the Email tab, select your email account.
Click Change.
Uncheck “Use Cached Exchange Mode to download email to an Outlook data file.”
Click Next, then Done.
Restart Outlook.


Before disabling Cached Mode, move any scheduled emails from the Outbox to the Drafts folder to ensure they sync with the server. After switching to Online Mode, go to the Drafts folder and send the messages.

You won’t see these messages in Outlook on the web, so you’ll need to trust Exchange. To verify it’s working, create an email to an address you can check on your phone, set a 15-minute delay, and click Send. Close Outlook. If you receive the message in 15 minutes, the setup is correct.