A significant bug has been found in VPOP3 v6.10 build 2698 which can lead to settings being corrupted. This is triggered by changing any settings on the Settings -> Admin page. (Note that most users do not access this page, so it is unlikely you will be affected by the bug, but it is better to be safe than sorry).
This problem does not affect other versions of VPOP3, only v6.10.
This problem will be fixed in v6.11, but there is also a patch available immediately which can be applied to v6.10. If you have VPOP3’s auto-updates enabled (on Settings -> Misc Settings), then it should install the patch automatically for you, otherwise you can download the fixed ‘utils_admin.html’ file from here, and copy it into the VPOP3\_webmail\admin folder.
If the VPOP3 automatic update has worked, then you should receive an email telling you about the update, but you can check by going into the VPOP3 settings and going to the About page. After the version number it should say “(Patch 160914a)” if the patch has been applied.
You can check whether the bug applies to your installation by going to Settings -> Admin Settings and go to the Message Targets tab. This should show a list of items with drop-down selection boxes. If there is a problem then you will see a very long list of hundreds of items, including strange entries, including \ and ~ characters. In that case, do not press the Submit button on this page, until you have downloaded and installed the patch. If the page has been patched, then you will see a list of 40 or so items, all with more meaningful names.
If you have any questions, please contact firstname.lastname@example.org.
We apologise for any inconvenience.