How to fix “This message could not be sent. You do not have the permission to send the message on behalf of the specified user.”

This message could not be sent. You do not have the permission to send the message on behalf of the specified user.
(Microsoft Outlook - Send As)
This message could not be sent. You do not have the permission to send the message on behalf of the specified user.
(Microsoft Outlook – Send As)

1 Make sure the Desktop Outlook is closed

2 Open following path from Windows File Explorer

%userprofile%\AppData\Local\Microsoft\Outlook\Offline Address Books\

3 Cut everything within this folder

4 Create a new folder name it backup and open it

5 Paste to the backup folder

6 Try to launch Desktop Outlook and Send As again.


How to configure and use Send As in Exchange and Outlook

How to configure Office 365, Microsoft Outlook Send As & Force Oultook update Global Address List (GAL)

Keywords: Office 365, Oultook Send As, Force Global Address List (GAL) update, This message could not be sent

1 Configure Send As permission in Microsoft Exchange

1.1 Login to Office 365 Exchange: https://outlook.office365.com/ecp

1.2 Click on “recipients” -> “mailboxes” or “shared”

1.3 Double click on one of the mailbox from the results list

1.4 Click on “mailbox delegation”

1.5 Scroll to “Send As” section

1.6 Click on “+” button, add user who should have Send As permission for the mailbox.

1.7 Click on “Save” button.

2 Send As from Outlook Online

2.1 Login to https://outlook.office365.com as the user we have specified in step 1.6

2.2 Click on your profile image at top right corner

2.3 Click on “Open another mailbox”

2.4 Enter the mailbox we give permission to from step 1.3 and click on “Open”

2.5 Now you can send email from this email address.

3 Send As from Microsoft Outlook Desktop Application

3.1 Launch Desktop Outlook

3.2 Click on “New Email” button

3.3 Click on “Options” from Menu then click on “From”

3.4 Click on From, if the address you want to send as appear underneath the “From” button, select it, if not, Click on “Other Email Address…”

3.5 Type the email address you have configured from step 1.3

3.6 Now you can send email from this email address.

4 How to resolve following Error

Note: You may encounter following error after step 3.6

This message could not be sent. You do not have the permission to send the message on behalf of the specified user.

This message could not be sent. You do not have the permission to send the message on behalf of the specified user.
(Microsoft Outlook - Send As)
This message could not be sent. You do not have the permission to send the message on behalf of the specified user.
(Microsoft Outlook – Send As)

To resolve this issue, try following method to Force Oultook update Global Address List (GAL) to resolved the issue.

4.1 Make sure the Desktop Outlook is closed

4.2 Open following path from Windows File Explorer

%userprofile%\AppData\Local\Microsoft\Outlook\Offline Address Books\

4.3 Cut everything within this folder

4.4 Create a new folder name it backup and open it

4.5 Paste to the backup folder

4.6 Try to launch Desktop Outlook and follow Section 3 again to Send As, this time there should be no error.

How to remove Office 365 Account from Microsoft Outlook properly

Keyword: Sign out, remove account, delete account, Office 365 account, from Microsoft Outlook

1 Open Microsoft Outlook

2 Click on “File”

Microsoft  Outlook Menu bar
Microsoft Outlook Menu bar

3 Click on “Office Account”

Microsoft  Outlook - File
Microsoft Outlook – File

4 Click on “Sign out”

Now you are logged out from Outlook proberly.

Note: By only delete Outlook profile from Outlook settings, it does not remove your Office 365 account login details from Outlook, by following this guide, your Office 365 login details will be removed, you can still add your account again, instead of type your email address and automatically sign you in, after this guide, you need to manually sign in again.

How to fix Microsoft Outlook freeze issue

Keywords: Outlook, Office 365, Outlook Freeze, Outlook not responding, Microsoft Outlook

If you have connected Office 365 account in Outlook desktop, you probably will have Outlook freeze issue from time to time. Here is a quick fix might work, if it keeps saying connecting exchange server.

Enable Outlook Cached Exchange Mode

1 Make sure you have enough disk space for downloading all emails from exchange server. (Means your hard drive’s free space should be bigger than your used mailbox size)

1.2 To find out your free local disk space, you need to open file explorer. (In this example, 164 GB free)

Microsoft Windows File Explorer - C drive disk usage and free space
Microsoft Windows File Explorer – C drive disk usage and free space

1.3 To find out your mailbox usage, you need to open Outlook, click on File from menu bar

Outlook Menu bar
Outlook Menu bar

2 Have a look on “Mailbox Settings” section, you will see how much space used. (3 GB used in this example)

Outlook Menu bar - File - Account Information
Outlook Menu bar – File – Account Information

3 If you have enough disk space, continue. Click on “Account Settings” icon, then click on “Account Settings” from drop down menu

Outlook Account Settings
Outlook Account Settings

4 Select Click on “Change…” button

Outlook Account Settings Menu
Outlook Account Settings Menu

5 Check “Use Cached Exchange Mode to download email to an Outlook data file”, Drag the handle to right hand side to make sure all emails will be downloaded, click “Next” button to save settings.

Outlook - Exchange Account Settings
Outlook – Exchange Account Settings

6 Leave Outlook open for awhile (Actual time depends on how big is your mailbox and how fast is your internet connection), so it can download all emails. When finished, you should not have freeze issue anymore.

Note: If you are still experiencing Outlook freeze issue, it can be other factors like plugins etc.

How to Fix: Outlook (Calendar) Search Results Incomplete

If you are sure the Outlook search results are incomplete, please try to rebuild your windows search index or reconfigure Outlook profile or reinstall Outlook.


In this simple guide, we are discussing that the Outlook Search results are not really incomplete.

If you search a calendar then sort by date, you are aware that some items are missing from calendar search results.

Try scroll down, till the bottom of the search results, you might find there is a group named Recurrence: (none): xx item(s) which can include some missing items from the top of the search results, now right click on the column title

Outlook column name
Outlook context menu for grouping

Click on View Setings

Outlook context menu Advanced View Settings List

Click on Group By… button

Outlook context menu Group By

Select (none), Click on OK, OK

Restart the Outlook.

Do the same search on calendar, all results will be listed in one group, you should be able to find the missing ones.

If still not fixed, items are still missing without groups, refer back to top of the guide.