Yahoo is one of the most popular and well used free email accounts that I know of, but it's also one of the most notorious for spam and lots of it.
If you're planning to use Yahoo as your primary email address for your writing business like I do, there are a few things you should keep in mind.
While spam is nearly impossible to eliminate all together, you can minimize it by giving out your email address only to your clients and your agent or publisher who might need a way to contact you online.
Don't use your email address to sign up for writing programs, subscribe to blogs or other related writing activity. While it may seem like a good idea, it can also lead to unwanted spam. Make a separate account for those activities.
Never give out your email address to those free offers or product orders, etc. Create a junk mail account for this.
Keep your writing business account separate from your personal account that you may want to use to keep in touch with family and friends. This should also be a rule for your fans you'll want to keep in touch with.
And finally, it is always a good idea to create a paid account for your writing business once you can afford to do so. Not only will it eliminate a majority of spam, it's also more professional on your image verses a popular free email account like yahoo.