Drowning in Spam
 

Like an idiot, I used to click on "unsubscribe" links. Clearly I'm far too trusting. Unfortunately this means I now get upwards of 300 spam messages a day. This isn't a massive issue, as I mostly ignore my spam folder, except I do the odd real message amongst the same cliche messages.

Is there anything I can do to ensure that the messages from the "FBI" (Please open the attachment sir) or "Princes from Africa" get deleted straight away?

Thanks

That depends on a couple of things. What is your email server? gmail? yahoo? etc. These servers can be configured to filter out your spam messages (most of them, at any rate).
What is your email client? thunderbird? kmail? etc. You can configure your client to automatically deleted junk messages.
Between the two of these you should get very few spam messages that survive the culling process.
jdk

theres a gmail hack where you can put a dot (.) anywhere in the username to help filter spam.

I use Zoho e-mail IMAP through Icedove as my client. One or the other clearly marks it as spam and puts it in the spam folder, but I'm not sure which.

Be careful who you give your e-mail address to. Configure your spam filters. Eventually, you may want to get a new address, because it gets ridiculous after a while. One of my parent's e-mails was getting 3000 spam messages per day, and it was gmail, which I don't like.

I have a separate 'personal' email account and one I give to organisations, such as Linux Questions. Personal email gets spam as it seems people let anyone and everyone have their address books. Corporations, including Dropbox either get hacked or 'lose' the email address somewhere.

I would argue they're working pretty well. I would entirely ignore the spam folder if it weren't for the one or two false positives.

That's a problem and it only increases with increasing spam messages. Carefully crafted filter rules can help delay the inevitable need to switch addresses. Can you imagine sorting through 3000 spam mails to find a possible false positive ?

One option is to setup and run your own mail server with postfix for example. Once you do this, you have complete control over spam emails, i.e if you get repeated spam emails from the same source you can go as far as dropping the ip address of their MX server with iptables command. If this is too advanced for you don't worry there are other options, you can look into software called spamassassin which also requires you to run your own mail server. If you must use someone else's server like hotmail or yahoo you're limited to whatever Algorithm they are using. If you're mail server is managed by a system administrator at your workplace feel free to ask him to tighten up the whitelist/blacklist rules using software as well.

http://www.freemysql.org

The ISP I use has some controls on the web site for their SPAM bin. You can click on a message and designate it as not-SPAM. In your filtered mail bin, you can designate mail as SPAM.
This also updates their filters, somewhat. I expect you may have done this already, or not.
Some ISP have finer adjustments to their filters.
It is much preferable to filter the SPAM before you have to download it to your local computer.
Don't get carried away as they do not care much about old SPAM (a couple weeks is old).

The SPAM filter on your email program is another thing entirely. It has much finer controls, and Linux versions can do very selective filtering. But you would have to turn off some of the ISP SPAM filtering (if possible) to let problematic desired messages get through.
There is no point in letting it all through.

Unfortunately there is no way that I even begin to have to understanding required to run my own e-mail server. I guess it would be the most customisable.

I'll have a look at IceDove's controls and see what I can do.