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Best practices for senders

Yahoo Mail's mission is to deliver messages that users want to receive and filter out messages they don't want. The simplest way to ensure that your messages are delivered is to avoid looking like a spammer.

Our tips

Following these best practices and tips will help your mailings reach their intended Yahoo Mail audience.

Secure your mail servers

  • Update your software with the latest security patches.
  • Filter user-generated content before sending it, to prevent spammers from using your resources.
  • If your servers act as "open proxies" or "relays," spammers may attempt to send their own mail from your systems.

Be aware of SMTP reply codes

If your messages are being blocked, look closely at any SMTP Reply Codes our mail servers are returning and make sure you're addressing the problem:

  • Don't retry 5xx messages.
  • Retry 4xx messages - This is a temporary error.
  • Refresh your list periodically:
    • Consider removing or sending a reconfirmation email to inactive subscribers.
    • Sending mail to users who are not reading them, or who mark them as "spam," will hurt your delivery metrics and reputation.
  • Enroll in our feedback loop - If you're signing your emails with DKIM or DomainKeys, our Complaint Feedback Loop program can help you track and manage your spam complaint rates.

  Learn more: Check out our SMTP error codes and Complaint Feedback Loop help articles for more info.

Always make sure your emails include DKIM authenticated signatures

  • Check if you are DKIM signing the email. DKIM signature helps Yahoo authenticate that email is safe, secure and from the senders who claim to send it.
  • Not being DKIM signed makes your emails appear to be sent by a spammer.
  • See for information about DKIM.

Publish reverse DNS (PTR) records for your sending IPs

Yahoo is more likely to downgrade an IP’s sending reputation if:

  • There's no reverse DNS entry for your IP address.
  • Your mailing IP looks like a dynamically-assigned IP instead of a static mail server.

Consistently manage your lists  

Monitor hard and soft bounces as well as inactive recipients. Persistent emails to these addresses are a surefire way to get your connections deferred.

Send email only to those who want it

  • Use and honor an opt-in method of subscription for your mailing list, where subscribers actively verify their intent to receive your mailings.
  • Honor the frequency of the list's intent.
  • Honor unsubscribe requests quickly.

Segregate your mail streams by IP address and/or domain

If the same IPs are sending unsolicited commercial email, and your presumably valid email, then your reputation can be impacted. Have separate IPs and streams depending on your email content type.

Check your email content

  • Test your emails' visual look with image placeholders. Many users won't see images in your email by default.
  • Link to domains, not IP addresses.
  • Use standard ports.
  • Don't include HTML forms, JavaScript, or embedded objects (like flash or ActiveX.)

Be CAN-SPAM compliant

Regardless of where in the world you're sending your mail, make sure that you adhere to the requirements stipulated by the CAN-SPAM Act.

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Last updated: June 17, 2014