DMARC stands for Domain-based Message Authentication, Reporting and Conformance and it is yet another technology trick ISPs and ESPs use to ward off SPAM in addition to SPF and DKIM. DMARC is a configuration of a domain record that tells the receiving computer what to do with messages if they are coming from a computer with a different domain compared to the one specified on the "Reply To" field. For instance, at we configured our DMARC policies such that if someone else sends an email from their computer (which cannot have our domain), but set the Reply To as: "firstname.lastname@example.org", then the accepting computer should report this incident to us. So far so good? Well DMARC - being a relatively new technology - has been used sparingly for some time. Different companies were doing pretty much the same as us: just reporting these incidents. This changed in April 2014 when Yahoo! took a deep dive into DMARC requiring receiving computers to reject emails if they are not sent from Yahoo! computers. Soon AOL followed the path after Yahoo!, which means you also cannot use AOL-based return addresses.
How does DMARC affect email marketers?
If you are sending emails from our servers (or if you are using any other ESP), and you use your personal Yahoo! (or AOL) email as a "Reply To", then most ISPs like Microsoft, Google etc will simply reject your emails because Yahoo asked them to! The solution to this is to use your corporate email address. Yahoo! and AOL logic is easy to understand: they provide free email service to individuals. If an email address they provide is also used to send mass emails from another ESP, than this is kind of a violation of the agreement on your end (I'm not a lawyer, do not hold my feet to the fire:)). Instead of sending from email@example.com, you will have to switch to firstname.lastname@example.org to solve this problem.
If you are sending mass email on behalf of your company, use your corporate email for this. If you are a blogger, and represent yourself then take this opportunity to get your own domain and build a better brand for yourself! Happy emailing!