So I'm sure the last thing any of us wants is our email ending up in the dreaded "Spam" folder... Not only does it look bad but it may also cause delays or even completely missed emails.
Spam filters use quite a lot of different metrics these days to "guess" what is spam and what isn't, but one of the easiest ways to drastically increase this rate (especially for low volumes of mail, ie. not mailing lists) is to set up an SPF record for your domain/s.
There's quite a lot of background info on Wikipedia: https://en.wikipedia.org/wiki/Sender_Policy_Framework
In short, you need to add a text field on your domain name specifying what servers are allowed to send FROM your domain. Anything else is to be viewed as faked and can end up in spam. While you can not have any SPF record at all, or have one that allows anything, most mail servers would penalise you for this, so it's best to limit to only the servers that actually send legitimate mail for your account.
There's a few tools available but I like this one: http://mxtoolbox.com/spf.aspx
Go there, type in "yourcompany.co.za" and do a check.
If you get something like this then you don't have any SPF record set up:
If you get something like this then great, but be sure you've taken note of the IP addresses allowed and that they haven't changed since you set up your SPF:
The above means that I've specifically allowed TWO IP addresses only to send mail from my domain. (the first one is my website server, generally automatically generated mails, and the second one is my hosted email account server). In order to figure these IP addresses out you will either know in advance as the hosting will usually show an IP address your site is hosted on, or you can look up the A record, or just run "ping yourcompany.co.za" in the command line and not the IP address, or you will have to send a test message and then view the FULL headers to work out the machine that originally sent the message. It's very important that you figure out all of the valid channels where emails can originate from your domain. Usually you're going to have at least one email account sending from your domain, as well as a website that would want to send from your domain. You may also have hosted mailing lists or third party websites that send email from your domain.