It's unprofessional and someone who took the project seriously would've proofread. OP deserves it

Even when I email my own parents I proofread it. Just out of habit, and it's a good one to use. So for something THIS important, I would have read everything over and over again until I felt 200% confident it is good enough to send. I'm sure OP didn't mean it, but this could have and should have been avoided.

I agree about drastic measures. Would thay have pulled him for any other typo? And I proof read stuff, but I can still look it over days and even hours later and find mistakes.

Yeah but they didn't actually fire him. They just pulled him off that project and I guess put him on a different one, so I guess it's not really that drastic.

It's possible OP was pulled from the project because the client complained or requested it. As a business, you want your client to trust and be comfortable with the team. It sounds like OP's boss/company understands it was an error—after all, OP could've been fired. As to the proofreading of your own work: I'm an English teacher. I've worked professionally as a copy editor. I have advanced degrees in linguistics and rhetoric. Proofreading your own work is extremely difficult, even if you're a superb editor, speller, and grammarian. Your brain knows what you meant, so it often overlooks minor typos, spelling errors, missing words, and transposed letters. It happens to the best and most diligent of us now and then. I can't even tell you how many letters to parents I've sent home with minor errors in them—and I proofread everything extensively and obsessively. I once managed to misspell my own name and didn't catch it until a student pointed it out.

It's not drastic, it's business.

Not everywhere, here in Australia we refer to our mates as cunts!

That's only cause they are.

don't be so testicular

You cunTRIED

Agreed. If you couldn't be careful on an email, what could you do wrong on an important project?

Even a basic spell check would have picked up this mistake so yeah, OP deserves this one.

It sounds like the email had already been sent to the client, so it could not be corrected.

Exactly, OP should have right-clicked and corrected it.

Obviously, it was already sent. That's the whole point. My point is that they overreacted over something easily correctable. Unless they're completely doltish, then they could easily determine what OP was trying to say instead of lambasting him outright. It's literally ONE letter.

Spell check is only effective if you miss spell a word, it doesn't if you select the wrong word for replacement