Free (21 day trial) of site to check if your email server has been blacklisted.
(Under “select Toolset” you should indicate “Professional Toolset – 1 year with 21 day trial”)
You can run a number of tests on your email server immediately, then have 21 days to decide if
you want to keep the service or cancel. Annual service is $79 and fairly inexpensive and valuable
if you do a lot of email marketing.)