Follow the below instructions to combine all the desired PST files into one
Download and install the DRS PST Combiner Mac. Run it as administrator.
Now, click the Add File button to add desired PST files.
If you want to add an entire folder containing multiple PST files, press the Add Folder button.
Locate the desired file from the system you want to merge. Select it and hit the Open button.
Now, you will see all the selected files in the list.
You can remove any unnecessary file added to the list. Select a file and press Remove.
Also, you can remove all the selected items by pressing the Remove All button.
Click the Next button to proceed to the next step.
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.
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.
Tick the Join PST option. It allows you to join PST files means every file has a different directory within the resultant PST file.
After that, click the Next button to proceed further.
In the next step, choose what Outlook PST item you want to merge. Tick the Mail, Calendars, Tasks, Contacts, Journal, and Notes.
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.
After that, click on the Next button to move to the next step.
For saving all the combined PST files into a new file, select the Join in new PST option.
Otherwise, you can tick the Join in existing PST option if you want to save the resultant file into an existing PST file.
Click on the Destination button to define the saving location of the resultant file. By default, the destination is set to Desktop.
The Apply Password option to enable password protection to the output merge file. Tick this option and enter the desired password in the field.
For excluding all the duplicate mailbox items, Mark the Remove Duplicate Mails on basis of To, From, Subject, Bcc, and Body options.
Tick the Remove Attachments if you want to avoid merging email attachments. Enabling this option makes the resultant file precise and accurate.
After defining all the parameters, click on the Join button to combine all the selected PST files.
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
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.
Click on the Next button to proceed to the next step.
After that, select the Outlook PST items you want to merge. Mark Mail, Calendar, Tasks, Contacts, Journals, and Notes.
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.
Repeat the process for all the desired entries. You can also remove an incorrect entry by pressing the Remove button.
After that, click on the Next button to proceed to the next step.
Now, tick the Merge in New PST option if you want to merge all PST files into a new PST file.
Alternatively, you can also opt for the Merge in existing PST option for saving all Outlook PST files in an existing PST file.
Click on the Destination button and define the saving location for the resultant PST file.
To add password protection to the merged PST file, mark the Apply Password button and give the password in the desired field.
Select the Remove Duplicate Mail option as it removes all the duplicate emails based on to, from, subject, bcc, and body.
If you want to exclude all email attachments, select the Remove Attachments option.
At last, click on the Merge button to merge all the input PST files.
After completing the merging process, you will see a pop-up. Click OK to close it.