Several of my friends have the unfortunate habit of not bothering to type accent marks (here I use the term loosely to include diacritical marks such as the tilde and umlaut) in their Spanish emails. I suspect this is due to ignorance of how to do it, rather than laziness. But neither reason is an acceptable excuse, in my eyes. It's easy for us native English speakers to dismiss these miniscule markings as superfluous, because we don't have them in our own language and aren't used to paying attention to them. And typing them on an American keyboard does involve a bit of effort, requiring multiple keystrokes. Nonetheless, accent marks and special characters are not optional. Leaving them out is, at best, annoying for the reader in much the same way that spelling errors are. At worst, one can end up saying something confusing or downright nonsensical, as there are many cases in which an accent mark makes all the difference between two words.
I didn't always feel this way. In my early days of writing Spanish, I, too, dispensed with the accents and ended up writing something extremely embarrassing to a prospective pen pal. As any conversational Spanish speaker knows, the translation of "I am 27 years old" is literally "I have 27 years," or "Tengo 27 años." I dropped the tilde, thinking it insignificant. Ano, however, means something completely different from año; let's just say that it refers to a particular part of the body not mentioned in polite conversation.
Do yourself a favor. Learn to type accents properly.