yellow letters - to seal or not?

[Patrick Britton]

hi,

when sending yellow letters to find sellers, should I seal the envelop or keep it open.  one source says to leave open as it adds considerable mystery.

thoughts?

thanks! 

[Larry Turowski]

I use yellowletters.com and they do not seal.  

But people worry too much about optimizing, as though that is going to be the make or break factor.  Optimizing is  helpful to squeeze the most performance out of something that already works.  If you have a marketing campaign that works, optimizing will make it work fractionally better.  If you have a campaign that doesn't work, a fractional improvement is not going to make a difference.