What Is Pegasus Mail? Version, Mail Files and How to Move Your Mail
Pegasus Mail is the free Windows email client by David Harris. Learn who made it, which version is current, where it keeps your mail and how to move that mail.
Pegasus Mail is the free Windows email client by David Harris. Learn who made it, which version is current, where it keeps your mail and how to move that mail.
Pegasus Mail is a free email client for Windows written by David Harris. Pegasus Mail sent its first message in December 1989 and version 4.91 is current from August 2025.
Your mail sits in PMM folder files with PMI indexes on your own disk. Neither Outlook nor Thunderbird opens those files directly. Mercury is the matching mail server by the same author.
Copy your PMAIL folder before you do anything else. Then move to a new Pegasus install or sign in with IMAP or convert folders for another client.
Pegasus Mail is a free email client for Windows written by David Harris in New Zealand. Pmail is the short name and pmail.com is the official site.
Pegasus Mail sent its first message in December 1989. Version 4.91 arrived in August 2025.
Pegasus Mail keeps mail in its own folder files on your disk. You read mail in a classic window or a multi pane view. Filters and several address books sit on top.
Searches for Pegasus Mail come from two groups. Long time users want to know whether Pegasus Mail is safe to keep. Newer users have old folders on a disk and need a way to read them.
This page covers who made Pegasus Mail and what version is current. You also see where mail lives, how Mercury fits in and which routes lead to another client.
Pegasus Mail is a free Windows email client from David Harris. Mail sits in PMM folder files with PMI indexes. Version 4.91 is current. Mercury is the matching server.
.pmm files with .pmi indexesComparing mail clients? Mozilla Thunderbird and Microsoft Outlook both cover a client Pegasus Mail users compare. The email application guides list more.
David Harris made Pegasus Mail in Dunedin and sent the first message in December 1989. The Windows version followed in 1993.
David Harris built Pegasus Mail at a university in Dunedin, New Zealand. His history page written by David Harris says the first message went out in December 1989 and the program has been free on the Internet since February 1990.
The university had a new network and no mail system. Commercial options cost too much. Harris wrote a simple program in his own time and gave it away.
Wikipedia gives the early name ComNet Mail and a launch for Novell NetWare. The Wikipedia entry on Pegasus Mail also shows the shorter name Pmail. Its infobox and text disagree on December 1989 against February 1990. The pmail.com history page stays the better guide.
The Windows version and the first version of Mercury both appeared in 1993. Harris says he left his university job that year to work on the software full time.
He funded the work by selling manuals while the software stayed free. That is his own account from 2002. The pmail.com manuals page today says the manual is free and ships with the program.
Yes. Wikipedia says that in January 2007 an announcement said distribution and development had ceased for lack of financial support. User support then led to a restart later that month.
A second scare came in 2025. The developer news page says Amazon removed the author's ability to write to pmail.com in June 2025. He moved the site to his own domain.
David Harris wrote it and still develops it. His history page says no anonymous corporation stands behind the program. The Pegasus Mail home page credits him with the content.
The same page notes that he is the author of Mercury too. Both products carry his copyright notice.
| Date | Fact | Source |
|---|---|---|
| Dec 1989 | First message sent | pmail.com history page |
| Feb 1990 | Free on the Internet | pmail.com history page |
| 1993 | First Windows version and first Mercury | pmail.com history page |
| End of 2001 | Version 4.0 released | Wikipedia |
| Jan 2007 | Development paused then restarted | Wikipedia |
| 8 Mar 2014 | Version 4.70 released | Wikipedia |
| 14 Feb 2022 | Version 4.80 released | Wikipedia |
| Aug 2025 | Version 4.91 released | pmail.com developer news |
Wikipedia lists 4.91 as 8 September 2025 in its infobox and as 11 August 2025 in its text. The vendor says August 2025. This page uses the vendor date.
Want another retired suite story? Lotus Notes and IncrediMail show how a mail client ages out.
Yes. Version 4.91 of Pegasus Mail is current. David Harris released it in August 2025 and says more regular updates will follow.
Yes. The Pegasus Mail home page lists version 4.91 for Windows as the current official release. Its announcement dates the release to August 2025.
The author says that release is effectively the unrestricted form of the 4.81 public beta. That beta added Gmail OAuth2 support. He also says more than 100,000 lines of code changed to modernize the source for newer Windows versions like Windows 11.
A German build followed. The home page lists Pegasus Mail 4.91 in German from October 2025. Sven Henze made that translation.
The version 4.91 announcement quotes him on plans with the words "significant plans for Pegasus Mail going forward." He also expects more regular updates from this point on.
The March 2026 note on the developer news page adds detail. He says he will speed up work on Pegasus Mail once the Mercury 4.92 beta is out. It gives no release date for Pegasus Mail.
The support page points you to the Pegasus Mail Community site. Volunteers also staff a support mailing address as time permits. The author offers no phone or fax support.
Register on the Community site before you post because guests can only read.
That depends on one thing. If your mail account still works in the program then the program still gets updates. A release in August 2025 is recent for a small one person project.
Weigh the risk that one person holds the entire project. The 2025 hosting lockout and the 2007 pause both show it. Keep a copy of your PMAIL folder either way.
| Item | Status | Source |
|---|---|---|
| Pegasus Mail for Windows | Version 4.91, 32 bit, 17 MB | Downloads page |
| German build | Version 4.91, 20 MB | Downloads page |
| Mercury | Version 4.91 current with 4.92 in public beta | Downloads and home pages |
| Last page edit | 28 April 2026 | Downloads page |
| Author plans | More regular updates promised | Version 4.91 announcement |
Dates on the site vary by page. Some pages show edits from 2003 and 2021. Treat the downloads page and the developer news page as the freshest.
Pegasus Mail handles POP3 and IMAP accounts with rule based filters, a junk filter and several address books. Folders open in a classic or pane view.
Pegasus Mail does the standard mail job and adds depth for people who sort heavy mail. The vendor's Windows overview describes the main parts.
Folders come in two layouts. You get a multi pane view or a classic mode with one window per folder. Pegasus Mail can also mount other users' mailboxes on your desktop.
Filtering is the feature the vendor stresses most. The overview calls its rule based filtering the most capable around. A built in Bayesian filter learns from the spam you receive and moves junk to a junk folder.
Address books come in several copies with nicknames and full detail records. Distribution lists help with large mailing groups.
Accounts use standard protocols. The overview lists SMTP, IMAP and POP3. You can open several POP3 and IMAP mailboxes at once and preview a POP3 mailbox before you download it.
Wikipedia lists a tree view for multipart messages and raw header access. It also names a Bayesian filter that arrived in release 4.41.
Treat those as secondary points. The vendor pages are the safer source for what version 4.91 does today.
The overview calls the program feature rich yet small and fast. The downloads page lists the installer at 17 MB. The Windows overview asks for 15 MB of disk space plus room for your mail.
That overview text is older than the downloads page. It names Windows XP while the downloads page names Windows 7 as the floor.
| Feature | What the source says | Source |
|---|---|---|
| Layouts | Multi pane view or classic mode | Windows overview |
| Filtering | Rule based filters plus a Bayesian junk filter | Windows overview |
| Address books | Several books with nicknames and lists | Windows overview |
| Protocols | SMTP, IMAP and POP3 | Windows overview |
| Selective download | Preview a POP3 mailbox first | Windows overview |
| Mailbox mounting | Open other users' mailboxes | Windows overview |
Pegasus Mail reads mail from your provider and files it in folders on your disk. Plan time for setup because Pegasus Mail has many options.
Pegasus Mail is free and needs Windows 7 or later. Donations fund the work. No native Linux or Mac version exists.
Pegasus Mail costs nothing as a download. The Pegasus Mail home page calls it a free product. The donation page adds that the program survives on donations from its users.
Wikipedia labels the license donationware. It also says all versions were free until 2006.
The Pegasus Mail downloads page says both Pegasus Mail and Mercury require Windows 7 or later. It lists the installer as a 32 bit program.
A 32 bit program still works on 64 bit Windows. A thread on the Community site says the author sees no real benefit from a true 64 bit build.
Older vendor pages mention earlier systems. Wikipedia lists NetWare, MS-DOS, Win16 and Classic Mac OS in the past. Today Windows is the only supported system.
Not as a native program. The Linux and open source page describes many requests for Linux but states no plan to build it. The author weighed open source in 2005 and said in 2021 that it was not feasible.
Wikipedia says Pegasus Mail works under Linux with Wine. Treat that as a community route and not a vendor feature. No source checked lists a current Mac version.
Mac users who still hold Pegasus Mail folders can read the macOS guides for next steps. Thunderbird is the common landing client. Read Mozilla Thunderbird too.
No. The Linux page names a proprietary editor component as one barrier in 2005. His 2021 update adds funding and developer needs and calls an open source move not feasible.
| Item | Fact | Source |
|---|---|---|
| Pegasus Mail price | Free | pmail.com home page |
| Funding | Donations from users | Donation page |
| Platform | Windows 7 or later | Downloads page |
| Build | 32 bit | Downloads page |
| Linux | No native version | Linux page |
| Source code | Closed | Linux page |
Mercury has its own terms. Section 6 covers them.
Mercury is the mail server by the same author. Pegasus Mail is the client. Pegasus Mail works without Mercury on a single desktop.
Mercury is the mail server that David Harris wrote beside Pegasus Mail, the client. The Wikipedia entry on Mercury says the same developer makes both and that Mercury first appeared in 1993.
A client reads mail. A server routes mail to the right place. Mercury handles the second job for a network of Pegasus Mail users.
The Mercury overview lists routing and delivery, mailing lists with moderation and digests and a rule based filter. It also fetches mail from remote POP3 mailboxes.
Protocols include SMTP, POP3 and IMAP4rev1 with SSL on the servers. The overview presents Mercury as a companion to Pegasus Mail.
No. The Windows overview says Pegasus Mail can send and receive Internet mail on its own with SMTP, IMAP and POP3. Early versions leaned on Mercury for outside mail, according to Wikipedia.
A single desktop with a Gmail or provider account needs no server. Mercury earns its place on a shared network.
For some users. The home page calls Mercury a modestly priced semi commercial system that allows free use for private and nonprofit users. Commercial use needs a license.
The system overviews page says free use covers personal and family use plus charities and nonprofits. The home page lists a 4.92 public beta from April 2026.
Not by default. Pegasus Mail keeps its own folders on your disk. Mercury holds mail that waits for you on the server. Section 7 shows where the local files sit.
| Question | Pegasus Mail | Mercury |
|---|---|---|
| Job | Mail client | Mail server |
| Where it lives | On your desktop | On a network machine |
| Current version | 4.91 | 4.91 with 4.92 in beta |
| Price | Free | Free for private and nonprofit use |
| Source | Home page | Home page and overview |
Pegasus Mail stores every mail folder as a PMM file with a PMI index. New messages sit in CNM files until filed. Address books use PMR and PM! pairs.
Pegasus Mail stores mail in files on your own disk. Every mail folder becomes a pair of files in a home mailbox folder.
The default install folder is PMAIL on the C drive. A reply in the Community thread on moving to a new computer gives C:\PMAIL as the default. It gives C:\PMAIL\MAIL\ADMIN as an example user folder.
A PMM file holds the messages of one mail folder. A PMI file is its index. The Community thread from April 2011 on files copied to CD describes them as a pair that makes up one folder.
An older vendor FAQ says Pegasus Mail file formats are all plain text or close to it. Look at a copy only and never save changes.
A CNM file is one message that has arrived and not yet been filed. The CD thread describes a CNM as a single new message left in the new mail area.
Keep CNM files in your copy because they can hold mail you have not filed.
The forum reply on moving to a new computer names PMR and PM! pairs for address books. It says to copy only data files and leave configuration files alone.
Wikipedia says early versions used a proprietary folder format with .pmj and .cnm names. Later versions added the standard Unix mailbox format with an .mbx name.
The same reply points to the PMAIL.INI file. It names the working home mailbox location. Read that line first on any machine that holds an old install.
A search for *.pmm in Windows Explorer finds mail folders when the install moved. Pair every result with its PMI file before you copy.
Comparing storage? Thunderbird keeps mail in MBOX files and Outlook keeps local data in PST files and OST files. The basics sit in what a file format is.
Pegasus Mail connects over SMTP and POP3 or IMAP. Gmail needed App Passwords in 2022. Version 4.91 adds Gmail OAuth2 support.
Pegasus Mail connects to mail accounts through standard protocols. In Pegasus Mail you enter your address and server details and the program fetches mail for you. The Windows overview lists SMTP, IMAP and POP3.
With POP, mail downloads to your computer. If your provider then deletes the server copy then your PMM files hold the only copy. That makes your PMAIL folder the item to protect.
With IMAP, mail stays on the server. A new client can sign in to the same account and see the same folders. IMAP users lose less when a program changes.
Google switched off less secure app access in early June 2022. The vendor's Gmail page of 23 June 2022 says OAuth2 was still in Google's approval process. It describes App Passwords as the workaround.
The 4.91 announcement changes the picture. It says that release includes Gmail OAuth2 support. The Gmail page itself still carries the 2022 text. Check the help inside the program for current sign in steps.
Changing your master Google password voids every App Password. You then make new ones.
The same Gmail page says Yahoo and Microsoft and Apple mail services also use App Password schemes. Your provider publishes the current server names and sign in rules.
FileFix lists none of those here because they change. Use the provider's own help page and write the values down before you move.
| Detail | What the source says | Source |
|---|---|---|
| Protocols | SMTP, IMAP and POP3 | Windows overview |
| Multiple mailboxes | Several POP3 and IMAP boxes at once | Windows overview |
| Gmail in 2022 | App Passwords as the workaround | Gmail page |
| Gmail OAuth2 | Included in version 4.91 | Version 4.91 announcement |
| Support | Community site and volunteer list | Support page |
Copy the PMAIL folder first. Move to a new Pegasus install by copying data files. Move to another client with IMAP or a converted mbox copy.
Moving mail depends on where you go next. A new Pegasus Mail install takes your folders as they are. Thunderbird needs a converted mailbox or an IMAP sign in. Outlook needs a bridge.
This is the easiest route. The Community thread on moving to a new computer gives the steps a helper posted. Copy the PMAIL folder to the same location on the new PC. Then start the old program file once and close it right away. After that start the installer.
That reply says to copy only data files when you restore from a backup. It names PMM and PMI pairs for folders and PMR and PM! pairs for address books. It names CNM files for new mail.
The CD thread adds a warning. A helper there says to copy the pairs into the Mail folder and to clear any read only flags. Another helper names a community utility called PMRestArch for archives. FileFix has not tested it.
Two routes appear in Mozilla forum replies. A helper in the Mozilla support thread from August 2015 calls IMAP the cleanest way to move mail. Sign in to the same account and Thunderbird shows the folders from the server.
The Mozilla support thread from March 2022 covers files. A helper says that if you convert Pegasus mail to mbx files you can remove the .mbx extension. Copy them into Local Folders while Thunderbird is closed.
That reply does not explain how to create the mbx files and does not confirm the result. Test with one small folder first. Read Mozilla Thunderbird for the client and MBOX files for the format.
Thunderbird stores mail as mbox by default, as the Mozilla article on Maildir states.
Outlook stores local mail in PST files, which the Microsoft article on Outlook data files describes. Outlook has no direct reader for PMM files. The mail needs a bridge.
One bridge is a client that reads mbox files and exports on. A second bridge is a converter that creates PST files. Read PST files and Microsoft Outlook before you choose.
The sources checked document no address book export from Pegasus Mail. One Mozilla reply asks whether CSV export works and gets no answer. Open the address book menu in your copy of the program and look for an export entry.
Keep the PMR and PM! pair as a safe copy even if you export. An old file can still teach you what the book held.
Check the folder size first and the home mailbox second. The 2GB PMM limit and a wrong home mailbox cause most Pegasus Mail trouble.
Three faults cover most Pegasus Mail questions. The three faults come from different causes. Check them in this order.
David Harris replied in the Community thread on the 2GB PMM limit. He said the cause is old code in the foldering layer that predates 64 bit file support. It is not a limit of 32 bit programs.
A new foldering layer was about 90 percent complete in that thread. He said it was unlikely to appear in the first version 5 releases. The thread shows no posting date.
He planned a warning as a folder nears 2GB and a block once it reaches the limit. Check your version for that behavior.
Check the PMAIL.INI file for the working home mailbox. A new install can point at an empty home mailbox. Your old PMM files sit in the old folder.
Copy the data files into the new home mailbox and leave configuration files alone. The helper on the move thread says not to overwrite existing files.
That is unfiled mail. Copy it into the new Mail folder as the CD thread says. Keep the original in your safe copy.
A Pegasus Mail folder still puzzling you? Send us the file details and we will work through the folder with you.
Pegasus Mail uses PMM and PMI pairs for folders and CNM files for new mail. No vendor spec exists so the layout comes from community replies.
The sources checked show no public specification for Pegasus Mail files. Community replies and reference sites supply what follows.
.pmm, messages of one mail folder.pmi, index for the PMM file.cnm, one new message.pmj, plain text configuration like state.pmj.mbx, Unix mailbox format in later versionsC:\PMAIL per a Community replyA PMM file and an mbox file both pack many emails into one file. FileFix explains the shared design in MBOX files. A PMM file also needs its PMI index while an mbox file stands alone.
The reference site FileInfo says a PMM file begins with a 128 byte header followed by the ASCII text of the messages. The vendor publishes no such layout so treat the figure as secondary.
FileInfo calls a PMJ file a Pegasus Mail configuration file in plain text with bracketed sections. It names state.pmj at the top of an install.
Wikipedia lists .pmj as an early folder extension. The two sources disagree on its role so this page claims only what FileInfo shows.
No source checked publishes the PMI index layout. None gives the full PM! structure for address books. The version where .mbx arrived is also unclear.
Be wary of any tool that promises perfect format support. Test it on a copy and compare folder counts.
| File | Role | Source |
|---|---|---|
.pmm | Messages of one folder | Community CD thread |
.pmi | Index for that folder | Community CD thread |
.cnm | One new message | Community CD thread |
.pmr and .pm! | Address book pair | Community move thread |
.mbx | Unix mailbox format | Wikipedia |
Message stores share a few common designs. what a file format is explains these designs and the file format guides index covers every format we have written up.
Check the size. Section 10 covers the 2GB limit.
Find the old folder. Section 7 shows where PMM files sit.
Planning a move to Thunderbird? Mozilla Thunderbird covers the program step by step. MBOX files describe the mailbox storage it reads.
Curious about Mozilla clients? SeaMonkey bundles mail with a browser. Trojita reads mail over IMAP only.
Moving to Outlook? Microsoft Outlook explains how the program stores mail. Outlook holds local copies in PST files and OST files.
Missing an older Microsoft client? Outlook Express and Windows Live Mail have guides of their own. Windows Mail does too.
Working with a mail server? Lotus Notes covers one and Zarafa another. EDB files hold Exchange databases.
Chasing calendar or contact files? ICS files and MAB address books cover two kinds. OLK files come from Outlook for Mac. Windows error guides list fixes by error code.
Browsing wider? The FileFix category index groups the topics and the FileFix home page shows what is new. Send us the file details when your Pegasus Mail files behave in a way this page leaves unanswered.