What's is the purpose of presales?
 

Sending an email with presales questions will give us, the potential hosting customers, the opportunity to measure things like how fast the response is, how correct the answers are, the level of detail given and the attitude towards the customer.
Often times, as I already noted in the "Testing Support" article, the response coming from the sales department is not as rapid as one coming from support. Some of the big hosts with many employees go as far as not to answer sales inquiries during weekends, although support for customers is available during that time.
With that said, as a general rule, responses from the sales departments to inquiries made by email should not take longer than 24 hours. Obviously the sooner the response comes, the better.
Note that this article comes as a completion to the rest of the things that I wrote so far, so there are things that I do not detail or even mention here, but are presented in detail in other articles of mine.