To envelope a door drop or not

In my opinion to envelope a door drop is a trade off. When a leaflet not in an envelope lands on the door mat – it is there for the householder to see. They have to pick it up. At this point your leaflet will be visible and if it is of interest or relevant they will not throw the leaflet away immediately but will either action it straight away or put it somewhere where they will see it again to action later. If the leaflet is in a plain envelope certainly a percentage of householders will open the envelope to see whats inside at this point they will see the information on the envelope and then keep or discard the leaflet depending on the relevance as above. Some people however will discard the leaflet immediately without opening because they will regard it straight away as letterbox spam. There is some agument that with the Royal Mail the envelope will get some benefit of being with post and therefore be opened? but will the considerable extra cost of enveloping generate enough extra enquiries to pay for it. I have seen offerings in evelopes over the years and often there is a reply paid card aswell so that could be some justification of the envelope. However in todays modern age I think all that is needed is a high quality leaflet with a freephone number and a website address. Dont put the leaflets in an envelope and use the money saved to send out a higher number of leaflets.