A user with a Microsoft Exchange server mailbox wanted to prepare some messages to send later but didn't want to leave Outlook open or open it to send.
I want to schedule an email to send on the Exchange Server so that I can schedule emails to send while I’m on vacation without having to boot my laptop and open my email 1-2 times per day. I know how to do this in desktop Outlook, but you need to open Outlook on your laptop for this to work. Can I do this using Outlook on the web?
If you are using Office 365 mailbox, Outlook.com, or Microsoft Exchange 2019, you can now send later from the web.
When you defer sending a message, in either online or cached mode, Outlook will always show the Sent time as the time you pressed Send, not the time Exchange actually sent the message.
Use Online Mode
When you use an Microsoft Exchange mailbox (either on-prem or Office 365 Exchange online) you can send messages later, with Outlook closed, as long as you can set the account up in Outlook desktop using Online mode.
When you use online mode, the deferred messages are submitted to the Exchange message queue and held until the scheduled time as Outlook doesn’t have a local cache when you use online mode, so it can’t hold them at the client.
This only works if you have the account set up in Outlook in online mode. It will not work with Outlook.com accounts as they do not support online mode.
By default, Outlook sets Exchange accounts up in cached mode. You can check in File, Account Settings: open the account settings dialog, and double click on the account. Cached will be ticked by default when you set up the account, untick it to drop to online mode. The status bar should say 'Online', when you have cached mode turned off.
Before you disable cached mode: if you have the messages already in the Outbox move them to Drafts folder first so they will sync to the server. After you switch to online mode, go to the Drafts folder and Send the messages.
You won't see the messages if you look in Outlook on the web, so you just have to trust Exchange. To verify it is working, create an email to email address you can check on your phone. Defer it for 15 min from now and click Send. Close Outlook. If you receive the message in 15 min, it’s set up properly.