Email Deliverability

One of the common questions we get is “My Email did not get through to all recipients. What happened?”

Email deliverability is much less than most people know. According to Sendgrid, fully 21% of emails never make it to a users inbox. Given that RunSignup sends over 15 Million emails per month, that means over 3 Million never reach their intended destination.  There are many reasons for this as outlined in these excellent articles by MailChimp, Sendgrid. The fundamental reason why an email is not received is it got caught somewhere in the internet email chain as spam.

The first thing to recognize is that there are many, many spam filters when you send an email to a distribution list. Gmail, Comcast, Hotmail, Yahoo, MSN, AOL, and company emails all have a different set of rules for marking a sender or an individual email as spam. They also have different ways of dealing with spam, and in many cases your email may not even be in the spam folder a person can see.

There are a variety of spam filters in the market. One of the most widely used ones is an open source program from the Apache Foundation called Spam Assassin. It also uses a variety of tools. As a little example, it uses Vipul’s Razor, which :

“is a distributed, collaborative, spam detection and filtering network. Through user contribution, Razor establishes a distributed and constantly updating catalogue of spam in propagation that is consulted by email clients to filter out known spam. Detection is done with statistical and randomized signatures that efficiently spot mutating spam content. User input is validated through reputation assignments based on consensus on report and revoke assertions which in turn is used for computing confidence values associated with individual signatures.”

The simple way to explain this quote is that there are lots of computers all over the internet running lots of software that tries to look for spam, and it uses feedback directly from users, things like deliverability rates, etc. to mark various individual emails or email senders as spam.

This means results will vary depending on how you send your email (RunSignup vs. Mailchimp), what account you send it from (your return email address like, the content of the email (if you say you are a Prince from Nigeria or if you have too many or too few words or graphics, etc.), your past email habits (sending too many to too many addresses), poor past deliverability and acceptance (bounces, spam/junk reports, opens, reads, replies, etc.), and the email recipient provider (gmail, yahoo, comcast, etc.).

Why Care About Deliverability?

Well, obviously if you send email, you think it is important enough for the recipient to get it! But there are Anti-Spam laws with potentially severe penalties outlined in the Federal Trade Commission website:

“Each separate email in violation of the CAN-SPAM Act is subject to penalties of up to $41,484, so non-compliance can be costly.”

…And the penalty can be on each email address!

So How do I get Better Deliverability?

If you have a specific email that a participant is not getting your email, the best way to address this is have the recipient add your email send address to their address book. For emails from RunSignup like password reset or confirmation emails, have the recipient add “” to their address book.

For your email marketing or pre-race prep emails, there are a variety of things you can do:

Clean Email Lists. A great example of a clean email list is the list of current participants. They are current and your waiver probably gives you the opt-in that makes for high quality. Importing 10 year old lists is a pretty big risk, as the deliverability will be poor because of changed email addresses (people moved from aol to gmail!). The spam filters will spot emails like this, and will keep track of who sent it and from where.

Do not oversend emails. At RunSignup we have a monthly newsletter we have been sending out for over 8 years and it has great deliverability. We see some races beat their poor lists way too much.

Clean Emails. You can use an email tester like It will run your email thru some spam filters to see if they get flagged from something.

Custom Email Tags. Making each email different and specific, and including the person’s name can help. For example, an email client like gmail may include whether a person’s name appears in the text of an email matches the recipient as part of their algorithm for determining if an email is spam or not.

Start Over. If you have earned a poor reputation, start over.  Get a new email address, potentially even a new domain name. For example, you may need to change from to or something. And then make sure your lists are cleansed and your future emails have value to them.

What does RunSignup do to help?

Under the covers of RunSignup Notification emails is Amazon’s SES service, and under the covers of our Email marketing is Sendgrid, the largest email service and recently acquired for $2 Billion by Twilio.

One of the reasons we use two email systems is that the ones coming from SES are coming from RunSignup and have very high quality scores because they are all opted in and are in response typically to a request by the user at that time – like a confirmation email.

The Sendgrid account is used for all customer email marketing. We have this designed to use rotating IP addresses. This means if a race sends out an email that gets flagged from Spam, some spam filters or email systems like Comcast or Gmail might block that IP address.  We rotate that IP address out of service for a while, and we contact Comcast and have them add it back on.

We have a number of things we do like automatically remove duplicates, include addresses, and embed DKIM codes as well to help with deliverability. We also will remove offending users of our system, although usually a discussion with them will help explain what is happening and the race usually cleans up their lists, email and reputation.

While we try to do our best on deliverability, we are a free service and no not offer some of the advanced tools that services like MailChimp offer like Omnivore. That is one of the reasons we offer customers a nice integration with MailChimp for people who do the volume to afford a more sophisticated solution.

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