Will the coffee fit through my letterbox?

Our gift subscriptions are sent in compact cardboard boxes which fit through most letterboxes.  The measurements of the subscription boxes are - Height: 40mm, Width:180mm, Length: 270mm

They are sent by Royal Mail Tracked post, so if the package does not fit through the letterbox and the recipient is not in to take delivery a 'Sorry We Missed You' calling card will be put through the recipients door giving instructions on where to collect the parcel or to rearrange delivery for a date that is convenient for them.