SPF issue: what causes softfail?

Question

Whenever I use PHP to send emails to members of my site, the email ends up in the spam folder for most email providers like Gmail and Hotmail.

When I check the original

Answer 1

I found a very good post about spf check here. If you got your spf and other setting right and still getting email in spam folder wait for 3,4 hour as described in post

Google’s spam filters are very powerful. If you send too much spam to their server from an IP or IP block, they will block you for up to several hours at a time. You will receive spam, you will forward it. They will filter mail as spam that you don’t think is spam. No matter what, you will send email to Google that they think is spam, even if you disagree. By simply receiving more email than they appreciate in a given time frame, your forwarder will suddenly stop working for hours at a time (or worse).