I recently bought an item on eBay. I received an email through eBay that my item had shipped.

[terryawhile]

I also received an email directly from this seller to my mail application. My question: how did the seller obtain my email address, through eBay, PayPal?

[mcrlmn]

I believe both have your email address.

If it came from eBay, check your account settings to enable or disable various notifications.

If from seller, it is available in the transaction info on PayPal.