E-mail behavior: the top 3 of how NOT to do it

As a professional IT/developer kind of guy, e-mail is my main communication method with many people and customers. Generally speaking, people tend to use e-mail properly and efficiently, but nonetheless there are certain irritating habits that repeat themselves all over again and make me see red. Here's my top three:

1. Improper subject line. I get way too many e-mails with the subject saying "Hi!", "Offer" or "Web App". The subject line is (surpise!) about the subject of your message. Instead of "Offer", try something more descriptive like "Offer about C# ASP.NET web application development". Works wonders!

2. People who sign all their mails with just "John" or "Joanna" or "Paul". That's fine if you're a friend of mine or a relative, but if we've never met and it's a business e-mail you are sending, I would expect at least your full name, company name, maybe your address and most importantly your phone number. E-mail doesn't always work, and I need an alternative communication method. Besides, some things are simply easier to discuss over the phone. Of course, you don't need to repeat your full contact details in each reply, but at least your initial message should contain the full contact details.

3. Excessive (HTML) formatting and (re)sending of attachments. Plain ASCII mail does the stuff just fine for me, takes less bandwith and is more secure. In 95% of the cases, there is no real need to decorate your messages will all those fancy colors and moving GIFs. And what even worse, mail filters just think those mails are probably spam. Also, when I send you an 800K attachment and you politely reply that you got it, please don't again include the attachment in your reply.