Plus, it just makes sense to be professional by following up to check that the correct person received the message you were trying to send them. Then once you have them on the phone or they respond to your email you can recap your interest in their venue and pitch yourself for a gig.
By following up with your marketing efforts it communicates to the booking folks at a venue that you're serious about what you do. Now, I will remind musicians that, depending on the venue you're marketing to and trying to get a gig at, the booking person there is likely busy so be respectful of their time. For example, if the venue you're going after is a restaurant/bar that has live music and the owner is also the booking person it's probably a good idea to try and follow up sometime between lunch and dinner when the restaurant is likely to be less busy. That may be the difference in actually getting to talk to the venue owner or getting his/her voicemail.
It can also work to send a quick two sentence email (short and sweet is always key) identifying yourself and why you're writing, but the main purpose of the email should be to ask when a good time to call and talk further by phone would be. That way the booking person can get back to your email and the two of you can schedule a time to actually talk on the phone and then you know you have that person's attention. You do have to be careful about this approach because emails can go into spam folders if your email address is not a recognized address. Also, it's helpful to use an informative subject line that identifies a bit about your email, you and the purpose of your message to increase its chances of being viewed. For example: "Attn: [booking person's name] local musician seeking gig at [venue name]."
So remember, getting the word out to a particular venue that you're looking to book a show is only half the battle, following up can ensure that your message was received leading to an increased likelihood that you'll land the gig.
Check out more from Nick Venturella: business site and official music site
Nick’s previous Examiner articles
Rock out to burn out time management for indie musicians
A little planning can go a long way
Local begets national and international exposure
Professionalism in the music industry
The power of do-it-yourself publicity