CarePrecise Healthcare Provider Data

Email Bounce Adjudication


CarePrecise guarantees 95% valid email addresses, and will make monetary adjustments for hard bounces by reason of "invalid" addresses for any number of bounces over 5% of the original purchase. So, how can we determine which bounces are due to truly "invalid" email addresses, and what makes so many messages bounce? See the CarePrecise Deliverability Guarantee...


Sending Bulk Email

When hundreds or thousands of nearly identical emails are sent within a short period of time, software on servers in their path are triggered to perform "spam tests," and valid addresses may get labeled as Undeliverable or Rejected because they were mailed in the wrong way. See Getting Email Into the Mailbox for some of the things you'll need to do to get better results.


First, a Word About "Open Rate"

Up until recently, the "open rate" - the fraction of bulk email that has been opened by the addressee - was the gold standard for judging the effectiveness of an email campaign. This is rapidly becoming a problem, because more and more ISPs and email service (like Apple Mail) are removing the components of the email message that are used to track opens. For instance, with iOS 15, the Apple Mail app* will start running all images through a proxy server to remove those tiny image-based tracking pixels that report when and where messages were opened. 45% of Apple owners use Apple Mail, so this is a big deal. Furthermore, Apple Mail will also hide user IP addresses, which is used to determine locatins. Traffic will run through Apple servers and a third-party server to remove identifying information. Traffic sent from the user's device will be encrypted so that third parties can't see whapent users are searching for (and that supposedly includes Apple too). Apple is not alone in making these changes, and, taken together, they will render the "open rate" essentially useless. CarePrecise has ceased tracking opens in favor of tracking overall campaign ROI, and recommends that its customers follow suit as soon as practicable.
Read the article, "Apple's 'Mail Privacy Protection' is an Earthquake for Email Marketers"...


Bounce Reason Codes

Email bounce investigation is both a science and an art. The art is a challenge to explain, as are all things art. The science is easier, but, unfortunately, there is little deterministic information in some elements of a bounce report from any given email sending vendor. Interpreting these reason codes is especially difficult, because every email sending vendor has its own system and coding, and they are frequently at odds. Here are some of the common codes and what they mean, when found in a bounce report or verification report:


Valid. Email addresses that are verified as Valid are generally those that encountered few, if any, challenges along the way to an active mailbox. The specific result code (or result term) "Valid" is the gold standard, but other results besides strictly "valid" may not be "invalid,". Sometimes an address will be coded "Valid Catch-all," which causes a lower grading by CarePrecise, but the majority of such addresses will be delivered on subsequent attempts, and are not eligible for refund or credit.

Unknown. Sometimes the receiving mail server responds very slowly or may temporarily be unable to process requests. In this case, the email address will be coded as Unknown. Different servers may handle the Unknown condition differently, and the result they return may actually mean different things, everywhere from "we tried too many times to figure out if this is a valid address," to "our server is too busy or otherwise unavailable to even try right now" to "this looks like spam so just go away." In most cases, such emails can be re-sent or re-verified after 5 to 10 minutes, or at a later date, with a "known" result. We track email addresses that return Unknown, and after a certain number of verification or send attempts, we remove them.

Greylisted. These are valid email addresses, but they probably have an anti-spam filter, and should be understood to be very choosy about which senders and messages get through. There are some things to do in the preparation of an email campaign that can eliminate some of these results. Bounces may be caused by either the sender domain being blocklisted/blacklisted, or the content of the message is seen by a Bayesian match as spam. In many cases, there is a filter at the server that is deliberately set to reject email that even slightly resembles earlier messages that were seen as spam by the filter software. Unless information in the bounce report can indicate an invalid email address, CarePrecise won't refund or credit for addresses that bounced for this reason alone, but, because it indicates a lower delivery rate, we track these results, and after a certain number, we retire the email address. 6/1/2021 update: Larger numbers of healthcare provider email addresses are hitting tightened spam filters as a result of abuse by vendors of medical supplies and equipment, mostly overseas, during the pandemic. CarePrecise recommends following the guidelines on Getting Email Into the Mailbox to reduce bounces due to conservative spam filtering.

Undeliverable or Rejected. These deteriminations are meaningless without suitable context. Sometime additional diagnostic codes will shed some light, but email sending vendors usually do not offer it. Unless a solid determination can be made that an address coded Undelivered or Rejected is invalid, CarePrecise will not refund or credit for the bounce. If a more informational code can be found after subsequent re-verification, CarePrecise removes these email addresses after a certain number of times. When we receive a bounce report from a customer that uses these vague codes without additional diagnostic information, CarePrecise will run a re-verification, and refund or credit only if the emails are adjudicated to be, in fact, invalid addresses.

Disabled. For a number of reasons, email services like AOL and Yahoo will respond with a 500 code that means "this mailbox is disabled." This may mean that the mailbox is full, or that it hasn't been downloaded for an arbitrary length of time. The only way to catch the truly "bad" Disabled addresses is to make multiple send attempts. We downgrade email addresses that return Disabled, and after a certain number of verification or send attempts, we remove them from inventory. Because the email addresses you receive from CarePrecise are carefully vetted in this way, and because so-called Disabled addresses are almost always not, in fact, truly disabled, we do not refund or credit for these in most cases. However, there may be extenuating information that can be found to cause quicker removal, and refund or credit..

Invalid. Generally speaking, the specific codes "Invalid" or "Invalid Email" or "Invalid Domain" can be considered to indicate a truly invalid address. Email addresses that are coded in this way are removed from the CarePrecise email database immediately, if independent verification confirms. CarePrecise will credit at double the count (one email address equals two credits), or refund for the price paid if the order was paid, rather than charged to credits.


Successful email marketing to healthcare providers requires more than a list of valid email addresses, especially today, when providers have been blasted with spam during the COVID-19 pandemic. Educating yourself on proper techniques is a critical step to bypassing the roadblocks set up to protect providers' mailboxes from spam. If our email is worth delivering, we'll have to work to convince the spam filters of that.

See our information on improving email deliverability...



* CarePrecise does not endorse or advise against particular companies or services, nor does it receive payments for mention of any product or service.