Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
MAILER
As described in historical dictionaries
Patronymica Britannica (1860)
MAILER. 1. A fai-mer ; one who has a very small piece of ground. Jamieson. A cottager who gets some waste land for a number of years, rent-free, to improve it. Ibid. 2. Perhaps Maylor, ahundi-ediu Flintshire.