I was using an RSS feed of latest.rss pushed into MailChimp to send an email 3 times a week to subscribers… But MailChimp is now saying the RSS Feed Link isn’t valid. Anyone else having trouble?
I am appending the ?api=xxxx key on the end of my URL since my forum is restricted to only logged in users. When I load the RSS feed URL in my browser, it loads up fine. But I tried both MailChimp and Mailerlite to see if I could get the RSS to email setup and both of them say the RSS feed is invalid.
You can try running it through a validator: W3C Feed Validation Service, for Atom and RSS
I’m not a 100% sure but this may be related to how API authentication is changed. The API key and username parameter are now required to be supplied in the request headers. Does mailchimp support supplying custom headers to the request for RSS?
This article will help you frame requests appropiately.
Thank you, that post says that it shouldn’t change and the weird thing is when I load the URL manually it does load for me in an incognito window and it also seems to pass validation ( though with a lot of recommendations ) – Hoping I am not the only one that has had this issue…
I recommend taking it up with your email service provider. 
I hear you, but I tried the RSS feed url on 3 different providers and they all rejected it…
I was hoping that someone would have an easy fix or be able to point me to what might have changed recently.
Did you get this sorted out?
…I’m contemplating building something in Mailchimp that uses RSS feeds out of Discourse.