Are you having difficulty delivering your email marketing messages to Yahoo?

Delivering your email message to Yahoo has become more difficult than ever. They Greylist a huge amount of email based on too many concurrent connections. Below are some basic details and information published by Yahoo, and added to by us, in regards to delivering email messages to their users. Use common-sense settings for your email server sending marketing messages. While Yahoo has not published guidelines for numbers of connections you can concurrently use, we suggest not having more than 20% of your total email list contain any one single domain, including Yahoo. Start mailing at 2 threads or concurrent connections and monitor your smtp logs. This is a slow tedious process to make sure Yahoo does not defer your connections. Once your emails are accepted without being rejected or greylisted, you can start turning up the threads to deliver your email more quickly. Don’t be in a rush to deliver your messages. Work slowly and efficiently.

Send email only to those that want it. To avoid being perceived as a spammer, use an opt-in method of subscription for your mailing list. Don’t send too many messages to your list per week. All this will do is make people want to complain and click the spam button. Be smart about the messages you are sending.

Use email authentication such as DKIM. This will help us identify that the email is legitimately from you and, if you sign all your email, it will help Yahoo identify forgeries, too. In addition, using dedicated domains for different mail streams (e.g., transactional messages vs. marketing emails) is also a recommended practice. is a good resource for information about DKIM.

Segregate your mail streams
 by IP addresses and/or domains since Yahoo keeps reputation data about each IP address and domain you send from. For example, by segmenting the mail stream that delivers marketing mail from another that sends transactional messages, you make it easier for Yahoo to determine and assign each mail stream’s reputation.

Consistently manage your lists
 by paying attention to hard and soft bounces as well as inactive recipients. Persistent emails to these addresses are a surefire way to get your connections deferred. If your messages are being blocked, look closely at any SMTP Reply Codes or logs.

  • Don’t retry 5xx messages. If Yahoo rejects a message with a 5xx error, they will not accept it anytime soon. Retrying the message is a waste of time and it’s time to change your IP’s and domains.
  • Do retry 4xx messages. If we send a 4xx error, this is a temporary error and you should try sending the message at a later time.
  • Do refresh your list periodically. Consider cleaning and validating your email lists. Email Answers offers Email Cleaning and Validation Services which is a great way to get rid of non-deliverable and complainers from your email list.

Enroll in the Yahoo feedback loop program. If you are signing your emails with DKIM or DomainKeys, enroll for our Complaint Feedback Loop program so you can track your spam complaint rates and keep them in check. Go here to signup,

 Use a consistent “From:” header address. Your domain name is an important element of your brand. Using it consistently helps us and your recipients to distinguish your email from spam. Additionally, using a static From: address helps users who have set up filters to route messages to a specific folder.

Pay attention to your email’s content

  • Test your email’s look and feel with image placeholders. Many users won’t see images in your email by default.
  • Link to domains, not IP addresses. Yahoo warns users that IP address links are dangerous.
  • Use standard ports. Yahoo warns users that links containing ports are dangerous.
  • Don’t include HTML forms in emails. Yahoo warns users that submitting forms in email can be dangerous.
  • Don’t include Javascript in emails. The javascript is stripped out and will not run.
  • Don’t include embedded objects in emails (like flash or ActiveX). The objects are stripped and will not run.

Honor unsubscribe requests as fast as you honor subscribe requests. When a user unsubscribes, they don’t want to receive that mail anymore. Promptly removing them from the list should help prevent users from marking your messages as spam in the future.

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.

Publish reverse DNS (PTR) records for your sending IPs.
 If there is no reverse DNS entry for your IP address, or if it looks like a dynamically-assigned IP instead of a static mail server, Yahoo is more likely to downgrade its sending reputation.

Secure your mail servers. Ensure your mail servers are not open to abuse. If your servers act as “open proxies” or “relays,” spammers may attempt to send their own mail from your systems. Keep your software up to date with the latest security patches, and always filter user-generated content before sending it out, to help prevent spammers from using your resources and tarnishing your reputation.