Informally, this means that if you send me an email, by doing this you're allowing me to post it, including your name and email address, on my website or anywhere else. Generally I'll respect your privacy if you ask me to, but I reserve the right to publish your mail if we feel its content warrants this. If you don't like this policy then don't send an email.
Informally, this means that if you send me commercial email that you can't prove I asked you to send, you're agreeing to pay me 500 US dollars for each and every such email.
NOTICE TO BULK E-MAILERS WITHIN THE UNITED STATES Pursuant to US Code, Title 47, Chapter 5, Subchapter II, p. 227, any and all nonsolicited commercial E-Mail sent to any email address within the mcwalter.net and mcwalter.org domains, and any associated subdomains, is subject to a download and archival fee in the amount of Five Hundred Dollars US. E-Mailing denotes acceptance of these terms. Consider this official notification. Failure to abide by this will result in legal action.
You may belive you have received unsolicited email from my domains (mcwalter.org and mcwalter.net). While it may well appear that way, that's a misleading appearance. Spam emailers often (it seems now almost always) forge the "from" field of emails; it's trivial for them to make an email appear to come from anyone. I get a lot of spam that appears to come from myself.
No-one with access to this domain's email system uses it to send spam or other unsoliticed emails. So please don't send me angry emails asking me to remove you from my mailing list - I don't have a mailing list, and I didn't send you any mail.
Informally, I'd strongly recommend you not reply to such spam emails - doing so only tells the spammers that they're sending to an address which is being read by a real person. They're very unlikely to take heed of your protests. Similarly, clicking those "please remove me from your list" links they put on their emails is generally a very bad idea.
People sometimes email me to ask for permission to use images that are displayed here, or that I've uploaded to Wikipedia or Wikimedia Commons (or that they've found mirrored somewhere else, usually taken from Wikimedia). If you're here for that purpose, please read this section before emailing.
I really do try to be rational and reasonable about licencing. I don't see any point in trying to charge money to anyone who wouldn't otherwise be paying. But vexingly I receive requests that I think aren't reasonable, where people who would reasonably expect to be paying imagine they can get away with not doing so.
Some of my works (that's the Wikipedia stuff) are licenced under the GFDL and related licences. They're all explicitly marked as such. The GFDL is quite a complicated licence, and people mistake it to mean something like "it's on Wikipedia so I can do what I want with it". They're wrong. People mistake it for a public domain licence, and they're wrong too. I'm not a lawyer, and certainly not your lawyer, so don't ask me to clarify it for you. Almost every re-use I see of my work is, as I read the GFDL, illegal. Realistically I'm not going to sue people. But one can't rule out the prospect that, stricken by some future penury, I might not sell the copyright of those images to some sanguisuge copyright trolls. Wikipedia complies with the licence (mostly) - it's not for me to say that you do. To be safe, you probably want a commercial licence - see below.
If you are a student in primary, secondary, or university or college undergraduate institution, and you want to use one of my images in an essay, thesis, presentation, or other submission as part of that education, you have my permission to use my images, without charge, in that context. Please credit me, and once you're done I'd appreciate a copy of your submission. This does NOT apply to teachers, lecturers, professors or other educators preparing materials for such students. It doesn't apply to people doing postgraduate qualifications, but you have my sympathies, so mail me and we'll work something out.
You don't, as it stands, have permission to use my material. That doesn't mean I won't grant it, and depending on what you're proposing to do, I might well not want to charge you money. Please email me and tell me about you project; the more detail you can give, the easier things will be.
Some practical rules of thumb: