what should i be careful when sending email with PHP so it does not goes in spam(especialy Yahoo Mail)

i am building a web that sends email for reseting password, verifying email and newsletter.

what i want to know what should i do it does not go into spam?

now i am looking in SwiftMailer docum开发者_运维问答entation to see how it can help me

thanks in advance

Using a well tested library for composing the e-mail (like SwiftMailer) is a first step. It ensures that the mail is not classified as spam solely because of non-adherence to the relevant RFCs. Additionaly, SpamAssassin provides Some Tips for Legitimate Senders to Avoid False Positives.