I've work all day long on that crazy problem.
I created an HTML email that will be sent massively. I Use PHPMailer and I tried Mail Function. Both PHPMailer, it's SMTP feature and the native Mail Function works well.
GOOD - PASS THE SPAM FILTER
The problem is when I put a link in the HTML code, the email turns into SPAM. But not any links. If I put a link that the href is "http://www.google.com" then It passes the filter. Samething on my company domain name "http://www.sequencedigitale.com", it passes the filter as well.
<a href="http://www.google.com">This is Google Website</a>
WRONG - DON'T PASS THE SPAM FILTER
What turns me crazy is when I put the same domain name as the server that process the email submission. I have 3 domains names that point on that server, every of those 3 don't pass the filter.
<a href="http://careers.fieracapital.com">This doesn't pass the filter</a>
I checked on some Blacklist checkers and the IP isn't block on 100% of the lists.
The IP is 184.107.100.61
The problem happened to me on Hotmail, Outlook and on a Server runned with Plesk. It passes the filter on GMail.
Any help will be appreciated.
Thanks.
Carl.
email that will be sent massively.
That's sort of what spam is, but you can try to make it less spammy so it passes through more filters.
It's good to make the From address be one that's from the SMTP server (use Reply-To if you want replies). If you can get an email server that's already reputable, that will get you closer to your goal.
It's mostly dependent on the proprietary filters Microsoft is using, so there's not a whole lot that can be done.