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Simple Ways to Open Another Mailbox in Outlook

Published By Aldrich Calvin
Anuraag Singh
Approved By Anuraag Singh
Published On August 2nd, 2023

Having access to multiple emails simultaneously is an absolute necessity in the modern work environment. Fortunately, Microsoft came up with an answer for “how to open another mailbox in Outlook” by adding a delegation feature. Using it employees can get access to each other’s mailboxes and continue business operations as usual. 

Therefore, in this article, we explain a variety of ways through which users can add a separate mailbox apart from their own. However, before we can go to the main task it is important to ensure that some key conditions are met.

Prerequisites to Access Another Mailbox in Outlook

Here is a list of actions that must be completed otherwise opening someone else’s mailbox is not possible.

  • Employees and admins must be aware of the task to avoid any complications.
  • A user who wants access must have the permission of the owner. 
  • Both users should belong to the same company domain.
  • Use a high bandwidth connection to answer how to open another mailbox in Outlook.
  • Ensure that the Outlook version you are using is compatible.

Read More: Stepwise Instructions On How to Create a Microsoft 365 Group Effectively

With these prerequisites out of the way let’s start with the first method.

Add Another Mailbox in Outlook via Manual Sharing

Follow these steps to get the job done:

Desktop Version:

Step 1. Launch Outlook. 

Step 2. Then, go to the “File” tab.

Step 3. Pick “Open & Export” to proceed. 

Step 4. Choose the bottom-most option “Other User’s Folder” & move further toward the answer of how to access another mailbox in Outlook email client.

Step 5. Then in the window that pops up, either type in the name of the mailbox whose permission has been assigned to you or press “Name…” and pick one from the list. 

Step 6. Next, choose the type of folder (Inbox, calendar, etc) you want to open. 

Step 7. Finally, click on “OK”.

Outlook Webmail:

Step 1. Login to webmail.

Step 2. Then, click on your name present in the upper right corner of the web navigation bar.

Step 3. Select the “Open another mailbox” option to add the mailbox of your choice.

Step 4. Lastly, type in the email address of the shared mailbox and select Open.

The other mailbox will appear below your personal one. However, sometimes this method doesn’t work. Don’t worry as there is an alternate way where multiple users can gain access to a mailbox. Read ahead to know more.

Access Another Mailbox in Outlook Using Shared Mailbox

Here are the steps to set up a shared mailbox.

Step 1. Log into the EAC with either a global or Exchange admin account. 

Step 2. Then, visit the admin center, navigate to Teams & Groups, and hit the Shared Mailboxes page.

Step 3. When you are on the Shared Mailboxes page, click the “+ Add a shared mailbox” button. Type in the desired name for the shared mailbox. Moreover, this will automatically generate an email address, however, you can edit it if it doesn’t fit your needs.

Step 4. Press the Save Changes button. Wait for a while before attaching the members.

Step 5. Once the mailbox is ready you can Add members to this mailbox. Every user who becomes a member can view both incoming mail and outgoing replies.

Step 6. Press the “+Add members” button. After that toggle the checkmark next to the users that need access to the shared mailbox, and then select Save.

Step 7. Press the Close button. 

Additional Info: Learn How to Add a Room Resource in Office 365 via this Simplified Guide

Disadvantages of the Manual Solutions and Its Resolution

In case both approaches fail to give the desired result you may be facing one of the below-mentioned problems:

Problem: Appropriate Permissions Not Assigned.

Solution: Use the Powershell command below:

Add-MailboxFolderPermission -Identity user.origin@domain.com -User user.target@domain.com -AccessRights Owner

Limitation: Powershell itself needs certain permissions to work not to mention the technical proficiency required to use the commands error-free. 

Suggestion: It’s just better to rely on an automated utility for this task.

Problem: Can’t Get Access to Shared Folder

Solution: One option is to wait as newly assigned permissions take some time to reflect on the live server. Otherwise, attempt manual one-to-one sharing and try to answer how to open another mailbox in Out

Limitation: Shared folder cannot be added to the account of users outside the company. Suggestion: The professional way to back up and share emails can get around this issue.

Problem: Automapping Feature Slowsdown or Crashes Outlook.

Solution: Turn off ‌automapping while setting up an account and enable it once the account setup is complete. Moreover, you can apply the set of Powershell commands given below for this:

Remove-MailboxPermission -Identity <UserMailboxIdentity> -User <UserName> -AccessRights FullAccess

Add-MailboxPermission -Identity <UserMailboxIdentity> -User <UserName> -AccessRights FullAccess

Limitation: Powershell is a complicated tool and any wrong query can jeopardize the data. Suggestion: The advanced software can be operated regardless of technical skill.

Open Another Mailbox in Outlook in an Automated Manner 

If you need to access your important emails offline, SysTools Office 365 to Office 365 Migrator is the obvious choice. With its user-friendly interface, even those who are not tech-savvy will find it easy to use. On top of that, the tool is highly recommended by professionals due to its robust algorithms and secure protection. Get started today and experience the power of the tool

Download Tool Purchase Now

The steps to use the tool are quite simple to follow:  

Step 1. Launch the software & set up the source (Office 365) and destination (Office 365).

Launch the Tool

Step-2. Select the workload and apply the date filter to get the most precise data.Apply Workload and Date Filter

Step-3. Then, enter & validate admin credentials for the source and destination.

Validate Credential

Step-4. Use any one out of Fetch, Import, or Download options for mapping.

Map Users

Step-5. Once mapping winds up, validate all available user-level data.

Validate User

Step-6. Finally, click on Start Migration and begin the download by pressing “Start”.

Start Migration

Some of the core features that established it as the market leader are as follows:

  • Multiple modes of user validation are available.
  • Both summarized and detailed report formation.
  • Incremental and Delta transfer options.


In our answer to “How to open another mailbox in Outlook,” we covered two different approaches. Moreover, we saw all the disadvantages faced during each one of them. Additionally, we found how a professional utility is a smart choice to not only avoid manual problems but gain other advantages as well.