Don’t send emails directly

How can I configure Outlook so it will not directly send my email when I click the Send button?

There are various ways to do this, but it depends a bit on what you are trying to achieve. Below you’ll find an overview of which options are available to you and an example of when it could be hand to use that solution.

Place Outlook in Offline Mode
This is handy when you also don’t want to receive any emails or don’t have any Internet access at the moment. To do this use;
File-> Work Offline

Disable “Send immediately when connected”
You can use this option when you want Outlook to only send messages during the scheduled send/receive interval (for instance, every 30 minutes) or if you don’t have an Internet connection available. Note that it could still occur that your message will be sent near instantly when you send a message right before the automatic send/receive interval takes place.
Tools-> Options-> tab Mail Setup-> option: Send immediately when connected

Set it for current message only
If you have finished writing your message already but do not want to send it out before a specific time, you can set a “Do not deliver before” property on the message and specify a date and time for when the message should be send.
Note that if you are not using Exchange, Outlook must be running in order to process the message at that specific time. The message will be send out with the first automatic send/receive interval that occurs after the configured time. So if you have scheduled your message for delivery after 7:30 and your automatic send/receive interval set to 30 minutes, it will be send at 7:31 if the last interval took place at 7:01 or be send at 7:59 when the last interval occurred at 7:29.

Delay all message up to 2 hours
If you want all your messages to hang in your Outbox for a certain amount of time because something else always comes to mind when pressing the send button (how you can rephrase something, adding another attachment, etc…) you can create a rule that can defer sending of all your messages from 1 minute up to 2 hours.
An example of how you can do that can be found here. You can set different conditions as well as setting no conditions at all if you want it to apply to all your emails. You can also set one or more exceptions such as that in case you have sent the message with the priority set to “High”, it will still send immediately.

Never send automatically
When you only want to receive your email automatically and what to be completely in control when the messages are sent, then you can disable the automatic sending for the default send/receive group;

1. Tools-> Options…-> tab Mail Format-> button Send/Receive…-> button Edit…
2. Here select your account and disable the option: Send mail items
3. Press OK to close the current dialog.
4. Press New…
5. You’re prompted for a name. Give it a name such as; Send Only
6. In the dialog enable the accounts that you want to control by enabling;
   Include the selected account in this group
7. Make sure only the “Send mail items” option is selected.
8. Press OK to close the current dialog to return to the Send/Receive Groups dialog.
9. Disable the option: Schedule an automatic send/receive every x minutes.
10. Press Close and then OK to close the remaining dialogs.

Now messages will only send when you press the Send/Receive button.