Fire it up and modify the configuration settings to your liking (Tools > Options) then close it.  This will create the configuration files.  Be careful not to overwrite any of these. HINT: A print out of the PMAIL.INI file from the Admin mailbox of the Win7 install can serve as a handy guide for matching many of the configuration settings.  Don't copy it though.

If you only have one POP3 & SMTP hosts then I suggest creating those manually.  It's possible to copy the files from the Win7 install but I believe new ones are the better way to go when so little effort is required to create them.

Migrating from a Win 7 PC to a Win 10. Have copied all user files from one

machine to a similar location on the new one. My MAIL location is in

Program(x86) directory on both PCs. I copied the entire MAIL folder

from the old to the new PC and installed the latest version of Pmail.

When I run Pmail I am asked for the user name and I enter "Admin"

since that is what is in the PMAIL.USR file. However, I keep getting

the error that the Admin user doesn't exist. Suggestions would be

appreciated. Both PCs are currently operational.

You said that your MAIL location is in Program(x86) directory on the Win7 PC.  Did you mean Program Files (x86)?  If so, this should not have been working because the file protections Microsoft built-in to both of its Program Files directories prevents the proper operation of Pegasus Mail. 

You also say you copied to "similar location".  A copy MUST be to identical locations.  The program files must be placed in an identical location on the new PC as they were on the old PC as must the mailbox (\MAIL) directory.

I suggest firing up Pegasus Mail on the Win7 PC then going to Help > About Pegasus Mail and clicking the "Info" button.  Copy the content of that display and post it into a reply.  It will help us to offer specific advice on how to migrate what you have over to the Win10 PC.

Pegasus Mail for Microsoft Windows
Copyright (C) 1992-2015, David Harris, all rights reserved
Electronic mail to support@pmail.gen.nz.

WinPMail version: Version 4.72.572, Feb 19 2016, build ID 572
Language resources: Standard UK English resource set
Extension Manager version: 1.14
Operating mode: Standalone
User name and ID: Admin, 0
Windows version: 6.0
Windows flag word: 0
WINPMAIL.EXE directory: C:\Program Files (x86)\PMAIL\Programs
Home mailbox location: C:\Program Files (x86)\PMAIL\MAIL\Admin
New mailbox location: C:\Program Files (x86)\PMAIL\MAIL\Admin
TMP environment variable: C:\Users\DICK&E~1\AppData\Local\Temp
TEMP environment variable: C:\Users\DICK&E~1\AppData\Local\Temp
LAN-based SMTP support: N, N, N
NetWare MHS support: N, N, N
Built-in TCP/IP support: Enabled
  - WINSOCK version: WinSock 2.0
  - WINSOCK path: WSOCK32.DLL
Commandline: -A
Active -Z options: 32768
PMR variable: (None)
PML variable: (None)
MAI variable: (None)
NB variable: (None)
Autofiltering folders: 0 (0 active, 0 inactive)
Last new mail count: 5
Message size soft limit: 0 bytes
Message size hard limit: 0 bytes
Attachment size soft limit: 0 bytes
Attachment size hard limit: 0 bytes

This output shows the Pegasus Mail program files and mailboxes in the Program File (x86) directory.  As such, this installation should not be functioning properly.

I strongly suggest a clean install on the Win10 PC to the default location of C:\PMAIL and then copying only mailbox data from the Win7 mailbox(es?) to the newly created ones. In the downloads area of this site is the document "Pegasus Mail files to copy to a new system guide" which was created specifically for your scenario.  Here is the direct URL.

http://community.pmail.com/files/folders/whitepapers/entry41852.aspx

Do not copy an entire mailbox directory because this will result in the failure of Pegasus Mail due to the numerous files that would contain paths pertinent only to the Win7 install.

I uninstalled the previous PMAIL and reinstalled in the default location, C:\.

The new Admin file is empty, is that correct? I thought that there would be

some default files. If that is correct, I will start copying the suggested files

as per entry41852.aspx.