the question you could perhaps ask of the webspace provider is what their sales:hit ratio would be.
They’ll never answer this question - I get many calls and emails
from online galleries, and when I’m tired of toying with them this is
the question I ask to end the conversation.
I don’t believe that 1% of online galleries have any sales at all -
maybe Guild.com does, but not many others. For the most part their
sole purpose is to collect fees from artists. One way to test this
is to search the web for their name; if it appears only in contexts
oriented towards artists, then you can be sure they aren’t trying to
sell to buyers.
And why should they? Buyers looking for bargains are a hard
suspicious market; artists looking for promotion are (forgive me) an
easy gullible market.
So unless you have extraordinary reason to believe there is a real
business going on - e.g. they are offering to buy work outright -
file these solicitations with the credit-card offers.