The problem-
Multiple spam emails from a single sender.
Multiple return paths and fake "from" lines.
All words are Spanish so not picked up by filter.
Subject lines vary with little repetition.

Tried so far-
Blocked several common Spanish words.

The question-
From the message source, what information can I use to block the emails? I am scared of blocking the wrong thing since I haven't a clue what most of it means.

To add-
I am reluctant to post the message sources here because I don't know which bits may be dangerous to show on a public forum.
To be honest they only arrived today so not a huge issue (yet) but I've always wondered what the relevant information in the message source was to block this kind of thing.
I am using windows mail on Vista.
Thanks in advance for any replies but I may not be able to respond for a few days.

I just switch to a new email address when spam gets annoying.

It may be possible to analyze the most common words in the emails, and try to filter those out.

Google Translate to decipher the Spanish. Also, I believe that one person wrote an excellent article on Bayesian filtering, I forget his name but Google could probably find the article (or one much like it).

Why not just open a gmail account and forward/pass all your mail from your existing/primary account through that. Gmail has fantastic spam filtering and I've never received a single spam e-mail or lost a single important message. And I've never even had to play with its automatic filter settings, which are very powerful, flexible and intuitive if you ever do need them. This way you keep using your current e-mail address and just let gmail do all the automatic spam filtering for you.

I use gmail. It's the accounts I discard when they get too spammy. I'm up to my 9th gmail account now.

Spam could be a lot worse.

Those are options thanks but going back to the original question, is there any thing within the source that I can use to block these ones in particular? In the spam options I can block more than just addresses and words. I'm away from that computer at the moment but I am sure there's stuff like domains as well.
The question is not so much about blocking spam in general. It's more about when you get loads from one particular sender using different email addresses and subject lines.

Mails are probably sent from a legitimate SMTP server so I would be careful about blocking the sending server.
Somtimes the outgoing provider includes a "sent for"-IP, you could consider filtering on that.

When I send email the SMTP server is my provider, to prevent misuse they place my own IP in to the headers.
Not all servers do this but it is something you could try.

Consider getting a Bayesian spam filter. It learns based on what you flag as spam. Using really interesting mathematics it learns from previous emails which words and IP's are related to spam.

heiowge: I'm not sure that works for everybody. I imagine most people would lose a lot of contacts if they kept switching emails. What gets you that much spam anyway? For me, I rarely have more than one a month that gets through the filter even though my address is all over the web.

Thanks Tom. I will look into that when I get home.
Bizarrely the emails have stopped for the time being on their own but it's good to have an idea how to fight them in the future.
Changing my main email would also be bad for me since there are people who sometimes get in contact from way back who I've forgotten about. After changes of computers and stuff my contacts aren't exactly up to date.
The reason I get spam is simply because when I started I didn't have a clue how things worked. If someone sent spam I replied asking them not to. If someone offered an unsubscribe option I clicked on it.

What? We shouldn't click the unsubscribe??? Why not? Serious question. Doesn't that help lessen the spam?

Roxanne,

If it is an unsolicited email, do not click "unsubscribe", it is often a trap; you are basically saying "yes, this is an active email account, I want more spam".

If it is a newsletter or other type of email that you actually asked for in the past, then most probably the "unsubscribe" button will work.

Further reading: http://www.dailycamera.com/business-columnists/ci_17566040

Skarabajo.

Thanks. I honestly didn't know that. I usually just ignore them, or click delete. I haven't got time to be bothered to go to the weblink and click unsubscribe again.