Travis from Mailgun Support here... There are several spammers located in the US and speak excellent English. Spelling and grammar isn't the best indicator. A s

Travis from Mailgun Support here... There are several spammers located in the US and speak excellent English. Spelling and grammar isn't the best indicator. A spammer in the US will typically have a good understanding of American communication style, thus, they are good at the social engineering aspect. The problem with spammers in the US is that it's pretty difficult to fully conceal your identity. There is always something in common or amiss with the account details. For example, if your billing address is based in the US, but you're connecting to infrastructure with IPs outside the US. Or better yet, chatting with me via an IP in the Netherlands. I think the best example of a US spammer was this guy attempting to promote his blog. (Or trying to warm up his account before sending spam) Each post was a rip off of an article from About.com. All the post dates were adjusted to appear that the site was online for months. His spelling and grammar were excellent. He had several flaws... The domain was just registered a couple days ago. The "Corporate HQ" address on the site was a post office in New York. The billing address was a UPS store in Nevada. He refused to talk to me on the phone or provide a physical address that I could send a t-shirt to. :-P