The Problem

When you try to send an email to a Yahoo, AOL, or AT&T email address, your message bounces back immediately with a delivery failure notice that looks like this:

"550 5.7.9 This mail has been blocked because the sender is unauthenticated. Yahoo requires all senders to authenticate with either SPF or DKIM."

Why is this happening?

Major email networks like Yahoo and Google have rolled out strict security rules to protect their users from spam and faked email addresses. When you send a message, Yahoo checks your domain's public settings to make sure you have given our servers permission to deliver mail on your behalf.

If your domain name is missing a special security directory line called an SPF record, Yahoo will automatically reject your email and send you this bounce message.

How do I fix it?

To stop your emails from bouncing, you just need to add our standard sending permission line to your domain name's DNS settings.

Log into your account dashboard where your domain's nameservers are managed, open your DNS Zone Editor, and add the following record:

• Record Type: TXT

• Host/Name: @ (or leave it blank depending on your provider)

• Value/Text: v=spf1 include:spf.cloudus.oxcs.net ~all

Note: Once you save this text record, it can take anywhere from a few minutes to a few hours to completely update across the global internet. Once it updates, your emails will automatically stop bouncing!

Frequently Asked Questions

1. The error message mentions "DKIM FAILURE," do I need a DKIM record too?

No. Yahoo's security rule explicitly states that you must authenticate with EITHER SPF or DKIM.

Our cloud email infrastructure automatically wraps an encrypted security code around your outgoing messages behind the scenes to keep them safe. Because this happens on our server backend, you do not need to manage any complicated custom DKIM settings in your domain menu. Adding the SPF record listed above is all it takes to satisfy Yahoo's rules and deliver your mail successfully.

2. What about DMARC? Do I need that to send mail?

DMARC is an advanced security guard rule that you can add if your business sends high volumes of daily marketing or newsletter mail. For standard everyday business email, a DMARC record is not required to pass Yahoo's filters—as long as your SPF record is properly saved, your messages will get a green light!

3. What if my SPF record is already added but my emails are still bouncing?

If you have verified that your SPF text record is correctly saved and has had a few hours to update, but your messages are still being blocked by Yahoo, our engineering desk will need to look at the hidden tracking data of the bounce message.

Please log into your Webmail portal, find the undeliverable/bounceback email you received, and download it directly as a raw data file. You can follow our step-by-step walkthrough here:

Rebel Cloud Email - How to Download a .EML File In My Webmail.

Once downloaded, open a help ticket with our support team and attach that .eml file so our supervisors can investigate the underlying routing path for you right away!