I know we did an FAQ on this.. it should be in the archives because I remember typing all these answers about a billion times .. but hell, why bother searching? No one does, it's so last-year .. anyway, in a nutshell -
1) The USPS needs a warrant to open mail, well, thats what they'd have you believe anyway - if they want in they will get in.. and while it's true that a private shipper such as FedEX or UPS can open anything they wish - they don't ... put simply, these places deal with millions of packages and letters each day, so they are not about to notice that the return address doesnt belong to the return name you listed or some shit like that..
Now to answer all these questions - (sorry, no fancy formatting or anything like that...
a)Do they sniff all packages or only those which look sucpiscous
ANSWER - Both. If they find a package that's ticking, leaking spores, smoking or is labeled "ILLICIT NARCOTICS, HANDLE WITH CARE" they can grab it and have a dog check it out, but what you usually see is the dog walking on the convery belt sniffing the mail as it flows through the processing system .. or they will sniff mail as it enters the facility..
b)other than having an obviously bogues return address what makes it look sucpiscious
ANSWER - Lets see... too much postage is a favorite - when a paranid drug dealer, anthrax mailer or mail-bomber wants to send something special to your door, they (usually) don't wish to go inside the post office because they fear they will get busted on the spot, so, they wrap it up and slap 7 times the correct amount of stamps on it "just to be safe" .. of course a package/letter with NO return address or a return address thats not in the same state where the article is being sent from .. everything else wouldn't raise an eyebrow (such as "over-securing" by using 4 rolls of duct-tape for a package the size of a toaster) ..
c)what drugs will the dogs alert to, heroin? fentanly? e? etc..
ANSWER - It depends on the dog.. most drug sniffing dogs can sniff out heroin, cocaine, and marijuana.. there are many new dogs trained to also alert on amphetamines .. they don't have fentanyl sniffing dogs as far as I know..
d) what is it that causes the dog to alert? The drug itself or impurities left over from synth
ANSWER - The drug itself is what they are trained to smell.. see, they can't detect "drugs", they simply alert when they pick up a scent they know, and they know that they get a reward when they find that scent.. you could have a pound of stinky crank that could be smelled across the room and the dog wont alert if it's only been trained to find marijuana and cocaine - sure, that meth may stink but it's not a scent that equals a reward for the dog ..
e)will an appropriate smell added to the package confuse the dog.
ANSWER - You mean like putting it in a jar of peanut butter? Or a bottle of pepper? Nope, sorry, these dogs can sniff out drugs like a female after cocaine..
f)what level of sealing (assuming gloves are changed at each step) is sufficent.
ANSWER - "wrapping" can be effective if you REALLY put work into it, and at some point you have to have a container that is TOTALLY AIR TIGHT - forget Ziploc, forget whatever else you normally use - remember, air = scent ..
I guess my advice would be to keep everything AWAY from the dope to avoind contamination.. start with an easy-to-manage bag (like Ziploc) .. fill it with dope then wrap it in saran wrap, now, put it to the side and sanitize your work area, change gloves, etc... you could then bust out with some of the air-tight Vac-Pack bags (they are truely air-proof) .. seal it up then clean everything including the outside of the bag, you could then just continue down this path until you have that piece of mind you were looking for - more then likely you couldn't pack it in such a way you have 'beat the dogs'..