Yahoo and AOL have changed some of their authentication records for @yahoo.com, @aol.com and other related domains, which affects our customers who use a yahoo.com or an aol.com email address as their RSVP address. There are similar issues with Hotmail, MSN and Live.com addresses breaking SPF authentication.
What email address should I use as my RSVP address?
We advise changing your RSVP address from these domains to one you have more control over and that’s a stronger representation of your brand, as you won’t be able to use these email addresses as your RSVP address and enjoy what we’d consider healthy deliverability rates.
If you use an @hotmail.com, @yahoo.com, @aol.com, @outlook.com, @msn.com or @gmail.com RSVP address, a warning will display on the Review & Send page but we will not prevent you from sending. The warning looks like this:
What happens if I don't change my RSVP address?
Because you're sending through our servers, mail servers that check authentication for your yahoo.com, aol.com, etc., RSVP will see that it’s broken and, based on Yahoo and AOL’s instructions, your message will be rejected. The short list of domains that check and that matter includes hotmail.com, yahoo.com, aol.com, outlook.com, msn.com or gmail.com, so it’s probably a majority of who you're trying to send to.
Yahoo uses a new authentication technology called DMARC, which combines DKIM and SPF to give more comprehensive protection for your domain. It’s a technology that mainly benefits larger entities who are more at risk to be spoofed or have their domain otherwise used to trick people into trusting malicious messages. Yahoo has set one parameter of DMARC to tell all mail servers that if DMARC authentication fails for yahoo.com, the message should be rejected. At this time, any mail server checking for DMARC authentication will refuse any message our customers (and our competitors' customers) sent through our system using a yahoo.com email address as the RSVP.
For more about this change and DMARC details, check out Word to the Wise’s blog post.