Q: how can i stop spam and dating requests

If the e-mails are from the same source or have a constant content, you can write a rule in Mail/Preferences/Rules. Sample below.

if you post your email publicly you will likely get spam

if you sign up for anything, you will likely get spam

if your email account is on a public provider (gmail, yahoo, aol) you will get spam.

if your email is given to anyone and they are on a public provider, have a public address book, have a hacked account, spam

it only takes one spammer to make your account a nightmare and propagate your address into countless other automated spam lists. If you are besieged by spam sometimes its best to create a new account and cut your losses. 

they call it spam for a reason, and this is the reason

https://www.youtube.com/watch?v=anwy2MPT5RE

1. Mail (Yosemite): Reduce junk mail in your inbox

or

2. third party Spam filter: http://c-command.com/spamsieve/

3. Server side filtering, log into your email hosting account and see if you can make some adjustments.