I've had a couple of people ask in recent comments about spam, and how it affects their queries. Whether having a Gmail account vs. a Yahoo account vs. Duckieduckie.com account would keep them out of the spam folder.
The sad, sad truth is that it doesn't matter what e-mail account you send your query from--there is always a chance that it will end up in an agent's spam folder.
Here's the layman's explanation:
This is because spam filters are generally Bayesian filters, which means that they look for "different words" than real e-mail, words that stand out as uncommon words. But because everyone uses the same words, as we all speak English, it's almost impossible to communicate without using words that spammers use. The spammers will literally append classic literature and dictionaries onto the end of the Viagra spam, in order to confound Bayesian filters.
Every time you mark something as spam, you're adding more words to the filter as "spammy", and forever after, anyone who uses those words in a real e-mail runs the risk of it getting sent into a spam folder or of it being blocked. In fact, a significant percentage of spam is not actually sent out to sell anything, but rather to confuse Bayesian filters.
Now there are solutions to this, involving setting up a special domain or a whitelist for queries, but the hard truth is that that's too much work and effort involved to do that. If any of my readers are computer science people, feel free to tell the rest of us exactly why and how you would do this--just know that I'm not going to do this and most likely, any other agent won't either.
The very simple solution is that you wait about 6 weeks to 3 months for an agent to get back to you on a query, depending on their published response time. If they haven't gotten back to you by then, send the query again from a different e-mail address. And that's how you try and play the spam game.
PS. I now own www.duckieduckie.com, but it doesn't direct anywhere and doesn't have a website yet. But oh yes, I will put up ducks there... =)