Some MTAs reject client connections unless the local name (used in the
HELO/EHLO command) looks like an FQDN. Currently, smtp-check always uses
`localhost`, which does not look like an FQDN.
This patch adds a command line flag to smtp-check to specify the
local name to be used.
Fixes https://github.com/albertito/chasquid/issues/37.
Amended-by: Alberto Bertogli <albertito@blitiri.com.ar>
Minor edits to the commit message, adjust flag name, go fmt.
