I accept a lot of email signups, but I’ve found I’ve had to be careful and check everything repeatedly (and block a few IPs in my logs) due to a bubbling up of spam signups.
Currently I use my email provider to handle my forms, but Ghost’s Zapier support is making me think that using the internal system would be a better bet. However, I think it would be a good idea to have a way to filter out spammy entries on the server end, akin to what WordPress does. Two solutions to this would be to add a captcha to the email signup—something that Ghost is not designed to handle straight-out—or to make available the use of a filtering service like Akismet to catch spammers.
Don’t know the complexity of this add, but I wanted to suggest it as it doesn’t seem to have come up before.