how to i stop people from emailing me?

Spam e-mail is, unfortunately, not possible to stop 100%. You can, however, block the e-mail addresses or set-up up a filter to automatically send all unrecognized e-mail addresses to the "Spam" or "Trash" folder.

To block the e-mail addresses, while within your Yahoo e-mail account, click the gear icon on the upper right and click the "Settings" link. From there there, click the "Blocked Addresses" link. Type or paste in the e-mail address you want to block and click the "Block" button. When you're done adding the e-mail addresses, remember to click the "Save" button at the bottom.

To automatically send certain e-mails to the "Trash" or "Spam" folder, while you have that e-mail open, click on the "More" drop-down menu option at the top of the e-mail, and click the "Filer E-mails Like This" link. From there, select the options for how you want to filter e-mails like that and click the "Save" button when you're done.

You may also want to check to see if there is an "unsubscribe" option or link at the bottom of the emails you're receiving. Someone may have entered the wrong e-mail address when they were subscribing to receive alerts or they may have intentionally typed in your e-mail address on job sites or marketing sites so that you would get the e-mails. Companies may also sell your e-mail address to marketing companies to use for solicitations via e-mail. There are also web bots that search through websites for e-mail addresses that are publicly listed to add them to a database that will automatically put you on the list to start receiving their spam e-mails. A publicly listed e-mail can be as simple as having your e-mail address visible to everyone on your Yahoo profile or other website profile. A web bot will pick that up easily.

It's good practice to always review the Privacy Policy of "free" e-mail accounts and to disable or unsubscribe from any marketing options that are usually enabled by default. Plus, it may be a good idea to review your profile on Yahoo and other websites that use your Yahoo e-mail address to see what is visible to everyone.

Switch to a better mail service, like GMail, which pre-screens spam, and then learns over time which ones you think are spam. I very rarely get anything into my Inbox that isn't a valid email. I do get lots of stuff that goes to the spam folder automatically (which you should scan occasionally to ensure you aren't missing something.

And, FYI, to make the conversion easier, you can have GMail get your Yahoo mail automatically if you can't forward the Yahoo to a newer account.