Plesk 11.x / Linux :: Multiple IP Addresses And Mail Configuration

I am running a VPS through 123-REG, Plesk version 11.0.9 with CentOS 6.4

I host 3 websites of my own (with 14 mail accounts)
4 websites for clients (with 10 mail accounts)
7 websites for clients (with 0 mail accounts)

The problem I have had in the last 2 weeks is that the server has been compromised once again by spammers.

2 weeks ago we had another instance and the support was even worse than before, I decided that the best way forward after irradicating the problem and correcting the source, and in the interest of each of my clients I decided to asign each client with their own IP address in the vain hope that if one client account is compromised the others will not be affected, 123-REG agreed that this is a solid solution so I purchased 5 additional IP addresses for the clients I host mail accounts for, (all of the said addresses were blacklisted when I was given them!!!) the reverse DNS was not set up correctly, and couldn't be through their control panel and some didn't match the SMTP banners, then I found out through them that the mail was still sent out through the Primary IP address anyway so if one client gets blacklisted they all still do.

Now they tell me that I can in fact configure Plesk to use each IP address for each client exclusively and they sent me a link to a support article that doesn't actually tell me how to do it.

I can do the following so far:

Log into puTTY and use the command: nano /etc/postfix/master.cf

Find the "smtp" record referenced in the article [URL]
1.1.1.1- unix - n n - - smtp -o smtp_bind_address=1.1.1.1 -o smtp_bind_address6= -o smtp_address_preference=ipv4
2.2.2.2- unix - n n - - smtp -o smtp_bind_address=2.2.2.2 -o smtp_bind_address6= -o smtp_address_preference=ipv4

although mine looks like the one below:
1.1.1.1- unix - n n - - smtp -o smtp_bind_address=1.1.1.1 -o smtp_b$

Is there something missing from the entry I have?

Assuming that 1.1.1.1 = the relevant IP Address for the client do I need to create an entry for each of my IP addresses?

Do I need to do anything with SMTP banners? If so how do I do it, and what do I need to do?

The article also mentions the default settings being restored each time you reconfigure mail settings and to consider a scheduled task, does that mean each time I set up a new mail account or a new client as I assume that I will need to repeat these steps in that case anyway, mainly because they will have a unique IP address that needs to be set up.