EMPLOYEE0The best answer to this question is as often as you feel comfortable! People will typically only donate when they get an email or Facebook message so the more you message them the more likely they are to donate.
However, as a general rule of thumb, you should probably email friends and family about once a week. People often procrastinate so sometimes it may take 2,3,4 or even 5 reminders before people actually pull out their wallets. But over the yesrs we've seen that "tactful persistence" is probably the one trait that all successful fundraisers have.
If you are worried that your friends and family might feel badgered if you keep emailing them over and over, here's a trick for you: ALWAYS make it a two-way street by offering the members of your email list something in exchange. Don't just ask for money, but offer them an update on how the fundraiser is going or a health update from the beneficiary of the fundraiser. You can also share a funny story, blog post or picture to keep people updated on your fundraiser's progress or the progress of the beneficiary. The key is to keep them engaged and interested in opening your emails.