how to stop getting hits from comment spam

Question

I have been hosting a photoblog using pixelpost, but have realised it was a haven for comments spam. I've since migrated the site to tumblr.

The original site was an add-on domain to my hosting plan and the site was available at a domain name as well as through a subfolder on my main domain.

This old photoblog is getting hits around 3 a minute 24/7 targeting example.com/subfolder. I've set .htaccess to issue a 403 for this folder.

the referrer is either blank or coming from my example.com

Is there any other ways to stop these hits? Will the spammers get the message from the 403 and eventually stop? how long can this take?

Were there any other steps I should take?

Thanks

snippet of error log:

[Tue Jan 28 08:56:23 2014] [error] [client 27.159.195.66] client denied by server 
[Tue Jan 28 08:55:59 2014] [error] [client 27.159.205.59] client denied by server 
[Tue Jan 28 08:55:11 2014] [error] [client 212.83.191.177] client denied by server
[Tue Jan 28 08:54:17 2014] [error] [client 212.83.137.63] client denied by server 
[Tue Jan 28 08:53:46 2014] [error] [client 27.159.193.51] client denied by server 
[Tue Jan 28 08:53:31 2014] [error] [client 27.159.195.66] client denied by server 
[Tue Jan 28 08:53:29 2014] [error] [client 27.159.195.66] client denied by server 
[Tue Jan 28 08:52:30 2014] [error] [client 117.26.254.132] client denied by server
[Tue Jan 28 08:51:37 2014] [error] [client 192.99.4.25] client denied by server co
[Tue Jan 28 08:51:33 2014] [error] [client 27.159.205.69] client denied by server 
[Tue Jan 28 08:50:45 2014] [error] [client 216.107.136.125] client denied by serve
[Tue Jan 28 08:50:45 2014] [error] [client 27.159.195.66] client denied by server 
[Tue Jan 28 08:48:41 2014] [error] [client 212.83.137.63] client denied by server 
[Tue Jan 28 08:48:37 2014] [error] [client 212.83.191.177] client denied by server
[Tue Jan 28 08:48:20 2014] [error] [client 5.153.235.237] client denied by server 
[Tue Jan 28 08:48:15 2014] [error] [client 209.148.82.163] client denied by server
[Tue Jan 28 08:48:14 2014] [error] [client 198.27.74.32] client denied by server c
[Tue Jan 28 08:47:27 2014] [error] [client 216.107.136.125] client denied by serve
[Tue Jan 28 08:47:19 2014] [error] [client 212.83.137.63] client denied by server 
[Tue Jan 28 08:46:28 2014] [error] [client 198.13.115.226] client denied by server
[Tue Jan 28 08:46:13 2014] [error] [client 27.159.212.23] client denied by server 
[Tue Jan 28 08:45:24 2014] [error] [client 118.175.92.74] client denied by server 

Answer 1

You could install mod_evasive on the server and with configuration, control how quickly you wish to blacklist IP's (say if they've hit your URL's more than 5 times in 10 seconds for example) - this will quickly blacklist the IP addresses that are bombarding your website.

Although eventually these should stop anyway if you've moved the site. Make sure that maindomain.tld does not contain a link to /subdirectory if some of these are showing as the referrer.

Will extend answer upon the response to my comment...