Question 1

Do you upload my files?

Accepted Answer

No. Mailtria runs entirely in your browser: files are read from your disk and results written back to it. Our servers never receive your mail.

Question 2

Which browsers work?

Accepted Answer

Current versions of Chrome and Edge on Windows, macOS, Linux and ChromeOS are tested. Other modern browsers are expected to work; saving results directly to a folder needs Chrome or Edge, other browsers download the files instead.

Question 3

Which files are supported?

Accepted Answer

Unicode PST files (Outlook 2003 and later), OST files including Outlook 2013 to 365, MBOX, EML and Outlook MSG. Old ANSI PST files (Outlook 97–2002), password-protected PST files and Outlook for Mac's OLM are not supported yet.

Question 4

How large can files be?

Accepted Answer

Results up to 50 GB. We have tested a 5.26 GB archive with 120,000 messages in Chrome; the limit in practice is your computer's free disk space, as results are kept in your browser's storage until you save them.

Question 5

Do I need Outlook?

Accepted Answer

No. None of the tools need Outlook or a Microsoft account.

Question 6

Is this a SCANPST alternative?

Accepted Answer

Yes. SCANPST (the Inbox Repair Tool) fixes the file in place and often gives up on badly damaged files. This repair never edits your file: it copies everything readable into a new PST and tells you exactly what could not be saved.

Question 7

What does the health check cost?

Accepted Answer

Nothing, and it needs no account. It shows every problem and how many messages can be recovered before you decide.

Question 8

Outlook says the file “cannot be accessed” or “is not an Outlook data file”. Can it help?

Accepted Answer

Often, yes. Those messages usually mean damaged internal structures. The health check shows whether the messages themselves are still readable.

Question 9

Is my file uploaded?

Accepted Answer

No. The engine runs inside your browser tab and reads the file from your disk. Results are written to your browser's private storage until you save them. Nothing is sent to a server.

Question 10

What can't be repaired?

Accepted Answer

Messages whose data is overwritten or missing cannot be brought back by any tool. Damage to the file's main index (very rare) is not supported yet. Password-protected and old ANSI PST files are not supported.

Question 11

How do I split a PST file without Outlook?

Accepted Answer

Choose the file above, pick how to split it and preview the parts. Outlook is not needed, and it works on Mac and Linux too.

Question 12

What is the PST size limit in Outlook?

Accepted Answer

Outlook 2010 and later default to a 50 GB limit, older versions to 20 GB, and very old ANSI files stop at 2 GB. Large files also make Outlook slow; splitting by year keeps each file small.

Question 13

Are folders kept?

Accepted Answer

Yes. Each part keeps the folder structure of the messages it holds.

Question 14

Will my original file be changed?

Accepted Answer

Never. Every result is a new file, and the engine checks that the source is unchanged before it finishes.

Question 15

How do I combine PST files?

Accepted Answer

Drop them above, choose whether matching folders are merged, preview, then merge. The result is one new PST.

Question 16

Will merging remove duplicates?

Accepted Answer

Merge keeps every message. Run Remove duplicates on the merged file afterwards to keep one copy of each.

Question 17

Does it delete anything from my PST?

Accepted Answer

No. It writes a new PST without the duplicates; the original is untouched.

Question 18

Why are duplicates in my PST?

Accepted Answer

Repeated imports, sync problems and merged archives are the usual causes.

Question 19

What is an OST file?

Accepted Answer

Outlook keeps an offline copy of a server mailbox (work Exchange, Microsoft 365, Outlook.com) in an .ost file. It only opens in the profile that created it; a PST opens anywhere.

Question 20

Can I convert an OST without the account or Outlook?

Accepted Answer

Yes. The conversion reads the file itself, so the mailbox, the server and Outlook are not needed. OST files protected by Windows encryption cannot be read.

Question 21

Why is the PST bigger than the OST?

Accepted Answer

Outlook 2013 and later compress the data in OST files; PST files are not compressed, so the same mail takes more space.

Question 22

What is not converted?

Accepted Answer

Folder views and rules stored in the OST are left out (listed in the report). Attachments the OST never downloaded from the server cannot be recovered.

Question 23

What is in the ZIP?

Accepted Answer

One .mbox file per folder, in your folder structure, plus nothing else. Unzip it before importing.

Question 24

How are the files named?

Accepted Answer

By number and subject (“0003 Quarterly report.eml”), in folders named like your PST folders, with unsafe characters replaced.

Question 25

Why MSG instead of EML?

Accepted Answer

MSG is Outlook's own format: it keeps everything Outlook knows about an item, including categories, flags, calendar and contact fields. EML keeps what an Internet message carries and opens in more apps.

Question 26

Do the .msg files open in Outlook?

Accepted Answer

Yes. They are written to Microsoft's published .msg format, the same structure Outlook writes.

Question 27

What is kept?

Accepted Answer

Subject, sender, recipients, dates, text and HTML bodies, attachments and the Internet headers. Calendar, contact and task fields are not converted (the item arrives as a message); attached messages are kept as .msg files.

Question 28

Can I import hundreds of .msg files?

Accepted Answer

Yes. Drop the folder; the import holds the messages in memory while it writes, so very large imports need about four times their size in free memory.

Question 29

How do I convert Gmail Takeout to PST?

Accepted Answer

Download your Takeout, unzip it, and drop the .mbox file (or the Mail folder) above. Takeout puts all your mail in one .mbox file, which becomes one folder in the PST.

Question 30

Does it work with Apple Mail?

Accepted Answer

Yes. In Apple Mail use Mailbox › Export Mailbox, then drop the exported folder here.

Question 31

Can I import thousands of EML files?

Accepted Answer

Yes. Drop the folder; the import holds the messages in memory while it writes, so very large imports need about four times their size in free memory.