With all (or at least most) internet service providers, there's a standard
email address postmaster@[service], e.g. [log in to unmask] that can be
used to bring messages like that to the attention of the internet service
provider. The email address abuse@[service] is also common but not
standard.
Susan Horein, LLLL
Madison Area Concert Handbells (MACH)
Wisconsin, USA
mailto:[log in to unmask]