[quote user="bfluet"]I can't duplicate that behavior.  In all of my tests the setting in Tools | Options | General settings | Basic settings remains set to Main Folder.  This setting is identity specific so check the setting in all identities.

[/quote]

It seems to be a display bug.  I've tested it and old mail goes to my selected default folder regardless of what folder appears to be designated.  It's just off-putting, is all.

I'm slowly paring down my "Old Mail" folder after discovering PMail would delete the PMM file if I deleted too many old messages at once (http://community.pmail.com/forums/thread/36096.aspx)

I've just discovered that, when I check  the "Name for default mail folder" (Tools | Options | General Settings | Basic Settings), the folder happens to be whatever folder I was last working in. So while it should be "Old Mail," if I've read a message in the "Junks or Suspicious Mail" folder, that is now the default mail folder.

I don't recall that being the case previously...

I can't duplicate that behavior.  In all of my tests the setting in Tools | Options | General settings | Basic settings remains set to Main Folder.  This setting is identity specific so check the setting in all identities.