Some of our customers have written in to ask about envelopes for use with 4"x6" photos.  Although standard #10 business size envelopes will work (9.5" x 4.125"), we prefer smaller A6 envelopes (also called #6 invitation envelopes) which are 4.75" x 6.5". There are also some envelopes specifically designed for 4"x6" photos. The mailable photo frame from photojojo.com is also a fun alternative. Below are links to some envelopes. If you find other types of envelopes, feel free to email a link to This e-mail address is being protected from spam bots, you need JavaScript enabled to view it