hi there
irrespective of whether you send a hard copy mailshot, or an email shot, that info needs to arrive at a required time, by that i mean that, if the client is happy with their current service, both the spec and the price then your marketing doesnt even touch them,
however if your mailshot arrives the same week that 2 or 3 staff in the office have complained that the toilets are dirty, or the MD hsa asked to review the cleaning cost, then your mailshot is of interest to the prospective client.
the secret therefore is to have a marketing plan, ie mailshot every two months, or even better when you build your database, and when you talk to those prospective cleints, one of the most important pieces of info that you can know, is WHEN DO YOU REVIEW YOUR CURRENT CLEANING CONTRACT?
with that answer you know when you need to send them a mailshot, or to call them or to knock on their door.
so your mailshots, are just another tool in the sales and marketing toolbox, and not a complete answer in how to get new clients.
regards
martin