Flat rate pricing eliminates the necessity to weigh packages or determine shipping service fees, given that the package weighs below 70 lbs. Buyers applying USPS-approved IBI postage meters that print the IBI with the appropriate cost marking (see 202.3.three) and transactional knowledge is electronically transmitted each day to USPS https://shipvista.com/partners/canada-post/canada-post-xpresspost-usa