Rules to shipping by lettermail?

I am new to selling and am unclear what the rules are to shipping by Canada Post Lettermail. In particular, for items like trading cards and game manuals, can these simply be mailed in a regular envelope with some rigid paper/thin cardstock to prevent damage? Is there anything else I should know that is vastly different from small parcel shipping? Thanks for any clarification.

View Entire Topic

Note to drwkny2

  By the way,  I should mention your listings are a lot better than  mine when I started.  Good photos too. Way to go!

InTime