Follow the below instructions to combine all the desired PST files into one
Step-1
Download and install the DRS PST Combiner Mac. Run it as administrator.


Step-2
Now, click the Add File button to add desired PST files.
Step-3
If you want to add an entire folder containing multiple PST files, press the Add Folder button.


Step-4
Locate the desired file from the system you want to merge. Select it and hit the Open button.
Step-5
Now, you will see all the selected files in the list.


Step-6
You can remove any unnecessary file added to the list. Select a file and press Remove.
Step-7
Also, you can remove all the selected items by pressing the Remove All button.


Step-8
Click the Next button to proceed to the next step.
Step-9
Now, the mailbox preview of the selected PST files will appear in the left pane. Tick the specific mailbox folders for merging and leave all unnecessary emails.


Step-10
The application provides two distinct options to add multiple PST files: Join PST and Merge PST.
To join multiple Outlook PST files, follow the below steps.
Step-11
Tick the Join PST option. It allows you to join PST files means every file has a different directory within the resultant PST file.


Step-12
After that, click the Next button to proceed further.
Step-13
In the next step, choose what Outlook PST item you want to merge. Tick the Mail, Calendars, Tasks, Contacts, Journal, and Notes.


Step-14
If you want to merge emails of a particular date range, select the Specific Date Range option. Choose an appropriate date range and click Add to add the entry.
Step-15
After that, click on the Next button to move to the next step.


Step-16
For saving all the combined PST files into a new file, select the Join in new PST option.
Step-17
Otherwise, you can tick the Join in existing PST option if you want to save the resultant file into an existing PST file.


Step-18
Click on the Destination button to define the saving location of the resultant file. By default, the destination is set to Desktop.
Step-19
The Apply Password option to enable password protection to the output merge file. Tick this option and enter the desired password in the field.


Step-20
For excluding all the duplicate mailbox items, Mark the Remove Duplicate Mails on basis of To, From, Subject, Bcc, and Body options.
Step-21
Tick the Remove Attachments if you want to avoid merging email attachments. Enabling this option makes the resultant file precise and accurate.


Step-22
After defining all the parameters, click on the Join button to combine all the selected PST files.
Step-23
After successfully combining PST files, you will see a pop-up message. Click OK to close it.

The below-mentioned steps help you merge multiple PST files into a single file
Step-11
Tick the Merge PST option for merging selected PST files. Unlike Join PST, the resultant file does not have a separate directory for each constituent file.


Step-12
Click on the Next button to proceed to the next step.
Step-13
After that, select the Outlook PST items you want to merge. Mark Mail, Calendar, Tasks, Contacts, Journals, and Notes.


Step-14
Select the Specify Date Range option. It allows you to merge emails of a particular date range. Choose desired dates in From and To fields and press the Add button.
Step-15
Repeat the process for all the desired entries. You can also remove an incorrect entry by pressing the Remove button.


Step-16
After that, click on the Next button to proceed to the next step.
Step-17
Now, tick the Merge in New PST option if you want to merge all PST files into a new PST file.


Step-18
Alternatively, you can also opt for the Merge in existing PST option for saving all Outlook PST files in an existing PST file.
Step-19
Click on the Destination button and define the saving location for the resultant PST file.


Step-20
To add password protection to the merged PST file, mark the Apply Password button and give the password in the desired field.
Step-21
Select the Remove Duplicate Mail option as it removes all the duplicate emails based on to, from, subject, bcc, and body.


Step-22
If you want to exclude all email attachments, select the Remove Attachments option.
Step-23
At last, click on the Merge button to merge all the input PST files.


Step-24
After completing the merging process, you will see a pop-up. Click OK to close it.