Warning: Google and Yahoo are preparing to enforce SPF/DKIM/DMARC compliance for high-volume email senders by February 1st.

Google and Yahoo, two major providers of free email services, are preparing to enforce a mass authentication process for email senders. This process requires the implementation of three authentication methods: SPF, DKIM, and DMARC. These measures must be implemented before February 1st.

Both companies announced this policy over a year ago, and it will affect senders who send more than 5,000 emails per day. The three authentication methods are DNS-based authentication mechanisms:

SPF: This declares the authorized servers that are allowed to send emails for a domain.
DKIM: This creates a digital signature to authenticate emails sent from authorized servers. DKIM utilizes a public key for the domain.
DMARC: This policy declares what recipients should do if an email fails SPF or DKIM checks, such as considering it as spam or blocking the email entirely. It also allows email servers to report any abnormalities.

For Yahoo, all email servers must implement SPF and DKIM, but DMARC is only mandatory for high-volume senders. Additionally, they need to ensure a clear opt-out process and maintain a low spam complaint rate.

TLDR: Google and Yahoo are implementing strict email authentication measures, requiring the use of SPF, DKIM, and DMARC. These measures aim to improve email security and reduce spam.