This is an independent guide, not the vendor's site. Buttons lead to stellarinfo.com; if a link carries a referral code, this site may earn a commission at no extra cost to you, and it does not change the advice. Prices and terms were read on stellarinfo.com on 10 November 2026.
Stellar Merge Mailbox for Outlook is a 64 bit Windows tool that merges or joins two or more Outlook PST files into a single PST, an Outlook profile, Office 365 or an Exchange mailbox, with switches to drop duplicates, deleted items and junk. The Standard edition is listed at $39.99 for a one year licence. The free demo shows the merged result in preview but cannot save it.
What the program does
Stellar Merge Mailbox for Outlook takes several Outlook data files and produces one. People reach for it when they have a PST per old account, a pile of yearly archives, or backups from a previous computer, and want everything in one file that Outlook opens once. The tool reads the source files without changing them and writes the combined data to a destination you choose.
It works in two modes. Merge pours the contents of matching folders together, so the Inbox of every source ends up in one Inbox. Join keeps each source apart under its own root folder inside the final PST. Either way you can limit the run to chosen folders, such as only Contacts or only Calendar, and skip duplicates, deleted items and junk. The step by step merge guide walks through both modes with the menu names from the manual.
- Folders handled: mail, calendar, contacts, journal, notes, tasks and to do items
- Password protected PST files are accepted once you type the password
- Archive PST files and files from different Outlook profiles can be combined
- A log records the mode, destination, start and end time, sources and folders
Three editions, one job each
The vendor sells the program in three editions. Standard covers PST merging. Technician adds mailboxes that are not PST files at all, and Toolkit bundles six further Outlook utilities. The pricing page explains the licence terms and which edition fits which situation.
| Edition | Listed price | What it adds |
|---|---|---|
| Standard | $39.99, 1 year | Merge and join PST files, duplicate removal, password protected files, log |
| Technician | $129, 1 year | Microsoft 365, Gmail, Yahoo, Outlook.com, DBX, NSF and 20+ mail clients into one PST |
| Toolkit | $199, 1 year (list $499) | Technician plus PST repair, OST to PST, split, compact, undelete, password recovery |
Pages in this guide
Read the review with a score and the limits if you are still deciding whether a paid merge tool is needed at all. If you only have two small files, the comparison with the Outlook Import/Export wizard shows what Outlook already does for free and where it runs out. The list of other PST merge tools covers the paid competitors and the admin route through Microsoft 365.
When you are ready, the download page has the requirements, the demo terms and the install steps in one place. The refund terms, which matter because the licence lasts one year, have their own page in the related list below.
Limits to know before you start
- It cannot merge a corrupt PST; the file has to be repaired first
- Microsoft Outlook must be installed on the computer that runs it
- 64 bit Windows only; no Mac or Linux version
- Every listed licence runs for one year; renewal terms are not stated on the buy page
- Installer size is not published by the vendor
Many PST files in, one tidy PST out. Try the preview first, pay only when the result looks right.
Preview your merge before you pay
The demo runs the whole merge or join and shows the result, including mail bodies and attachments. Saving needs a key.
Frequently asked questions
What is Stellar Merge Mailbox for Outlook?
It is a Windows program from Stellar Information Technology that combines two or more Outlook PST files into one. It can merge matching folders or join each file under its own root folder, and it can skip duplicates, deleted items and junk while doing so.
Is there a free version?
There is a free demo, not a free edition. The demo runs the merge and shows the result in preview, including message bodies and attachments, but saving the merged file needs a paid key.
How much does it cost?
On 10 November 2026 the vendor listed Standard at $39.99, Technician at $129 and Toolkit at $199, each as a one year licence. Toolkit was shown with a struck list price of $499.
Does it need Outlook installed?
Yes. The vendor's FAQ says PST files cannot be joined without Microsoft Outlook installed on the same computer.
Which Windows versions does it run on?
The data sheet lists 64 bit Windows 11, 10, 8.1, 8 and Windows Server 2012. A 32 bit system is not supported.
Can it fix a damaged PST while merging?
No. The vendor states that corrupt PST files cannot be merged. Repair them first, for example with a PST repair tool, then run the merge.