About once or twice a day I get hit by spambots (it's a similar pattern, so probably the same spambot? 4 subscriptions in quick succession...)
Is there a good way to deal with this?
Are you using email confirmation? Are they clicking the link and fully activating?
If they are, I would block their IPs at the server level. I find they don't use too many IPs.
Never use common email address's a subscribe address's or even in everyday work.
Like info, admin, support, sales enquire etc
They send spam to all common emails
Spammers use Bots to find forms to place comments on blogs, forums, etc.
Now they hit autoresponder forms and can damage your sending reputation.
Why, because everytime someone subscribe to your list the following can happen:
no confirmation email is sent but your Day 0 welcome message goes out. It reaches a fake email address 99.99% of the time from Gmail, Hotmail, Yahoo, etc...
a confirmation email is sent and it It reaches a fake email address 99.99% of the time from Gmail, Hotmail, Yahoo, etc...
When this happen once in a while, that's ok.
But like we have experienced, you could be under an attack...
we had over 2.3K of subscription in a 18 hours time frame and I can tell you, that's bad.
Not only you have to clean up you ar DB but also because your domain name is sending so many Day 0 or optin confirmation emails, the big free email provider dogs are going to punish you!
The best ways to avoid this are:
1) Block know spamming IPs
2) Put a captcha on your forms
3) Add a Agree to whatever you like tick box on your form
4) Block any countries you're not doing business with, server side on in your website .htaccess file.
5) Block bad bots in your htaccess file
These morons use bots to find "form", "submit", and any other good tags which could allow them to spam you.
While the email they use seems to be legitimate, the name or firstname is always a bunch of BS numbers or characters.
We experienced many of these attacks on email submit forms, ar optin forms, whmcs registration forms and other shopping carts registration forms.
I do believe there are ways to change the usual form tags and link them to an external non readable but still executable script to block once for all these attempts, but I'm not a programmer so I fight with whatever I have in my actual arsenal.
Wordpress: Wordfence, sucuri
Web form: captcha, agreement check box
Web server CFS blocking unwanted countries
Htaccess: everything I don't like or suspect.
Hope this helps.
PS. if you try to visit my websites but cannot access them, it's because I already caught ya! :)