You definitely can. I write awful horrible insensitive scathing emails to people, and then delete them in the morning without sending them. I get the catharsis, and I don't lose any friends (actual or potential) in the process - everyone wins!
The scary part is that delete and send are pretty close to each other in gmail.
How many times have you deleted an email when you wanted to send one?
In Gmail? Zero, because you can undelete.
If you act fast, you can unsend too.
how?
Enable "undo send" in labs and then just hit 'z' (assuming you have keyboard shortcuts enabled too).
Yes, absolutely. That's why I never fill out the To field when writing an email that I'm not sure I should send.
Without "To" field you risk to forget who you are angry at.
I type it into the top line of the email, cutting and pasting it to "To" right before I send. Helps prevents those "oops! sorry I sent you the previous email before compelting it because I accidentally hit the Send button."
I usually append an extra character to the To: email address so it bounces in case I accidentally send it
People in hospitality do that with their inner voices rather than blowing up at customers all the time.
I once heard someone say, "The quality of a man is measured by the size of his drafts folder relative to his sent folder."
Yes, you can. At least it works for me.
In these occasions I find myself writing a draft of a letter, then re-writing it 5 or 6 times as my anger subsides. What starts out as a 10-page tome usually turns into 3 paragraphs of "Hey, this wasn't so great, Here's how I'd love to see it done."