To reload the server you will need to do something like this.
1. In Pegasus Mail menu Tools/Internet Options select POP3
2. Click on Disable button for server. This will stop any further downloading to your PC
3. Go to folder holding all the messages you want to return and Bounce each message you want to reload to the server, using Forward menu button and check "Forward without editing" button, then click Send Forward
4. Repeat 3. for all messages you want back on the server
5. In Tools/Internet options, click POP3 tab
6. On the server definition you disabled in 2. above, click Edit.
7 Uncheck button "Delete on Server"
8. Click OK, then Click Enable button, to re-enable the POP3 service. Click OK to save definitions.
You will now be collecting incoming mail on the server until you either delete them in another mail client or use Selective Download feature of Pegasus Mail.
HTH Martin