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Custom vs Shared Sending Domains
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on 1/30/2024 11:24:00 AM

At CharityEngine, we offer two different configurations for customers to use when sending communications to their contacts.   We offer a shared sending domain and the ability to send your messages from a custom, unique domain.  Each option has its own advantages and disadvantages, and it is important to understand which one is right for you. 


First it is important to understand the reason for the distinction.   With regards to being a bulk sender, receiving mail servers, like Gmail, Microsoft, and Yahoo/AOL, tend to be very defensive against mass mailing.  This is because in most cases mass mailing is not legitimate, and there are many bad actors that utilize email to transmit dangerous content, and these servers are designed to protect their users against these types of senders.   There are several mechanisms in place that allow legitimate large-scale senders to identify themselves to these servers that their content is safe and should be allowed to be delivered.   These mechanisms are generally covered by DMARC.  DMARC stands for Domain-based Message Authentication, Reporting, and Conformance and is a technical standard that helps protect email senders and recipients from spam, spoofing, and phishing.  DMARC is a combination of SPF and DKIM, two different domain records that must be configured and maintained and receiving servers can query those records in order to identify if the sending server is authorized to be sending messages on behalf of the domain being used, and to verify that those messages have not been compromised during transmission. 


Unfortunately, DMARC only gets your messages to the mailbox, not to the inbox.   In order to determine mailbox placement, which is to say where in the recipient’s mailbox the message should go, most servers now employ a technique commonly called GreyListing.   GreyListing is a practice where receiving servers look at many different facets of a message, the sending domain, server, and how users have reacted to those messages previously in order to create a domain reputation.   For example, if your messages were delivered to user’s inboxes in the past, but were not opened, this will negatively affect your domains reputation.   Similarly, if you receive unsubscribe requests or message ‘spam trap’ mailboxes, your reputation will also become lower, and it is less likely that your messages will be placed in the user’s inbox.  Controlling, moderating, and effecting change to this reputation is a large and difficult undertaking, and receiving servers constantly change their detection methods and criteria for determining reputation. 

The unfortunate truth is that this system tends to be unfairly weighted against senders that do not generate enough messaging to maintain a reputation, either good or bad.   In this case, sending too few messages can lead to having no reputation, and no reputation is worse than a bad reputation.   Your reputation is what lets servers know that your messaging is welcomed by the recipients and that they want to receive it, and without a positive reputation, your messages tend to be classified into another folder, or into the Junk folder.   This is why CharityEngine employs a shared sending domain.  This allows charities with a smaller sending footprint to ‘band together’, establishing a good reputation that allows the shared domain to maintain a positive reputation, without any of the management of that domain being passed on to the charity.  

We allow you to set the Reply To address as well as to mask the sending address.  This means that your messages look like they are coming from you, and users are able to reply to you, but we ensure the domain reputation is positive and that your messages are delivered promptly to the users inbox.  

For Charities with a larger sending footprint, or Charities that have a large and established contact list, we have the ability to allow you to send from your own Custom Domain.   This means that your messages come from you, not from our Shared Domain.  For a Custom domain, you will need to have IP addresses dedicated to your domain, so that it can be established that these IPs are allowed to send on your behalf.  We require a minimum of 2 IP Addresses per domain, however as your list grows, we can scale up the number of IP addresses, which allows you to send more messages quickly.   Custom domains, and their associated IP Addresses also need to be ‘warmed’, which is a process of slowly increasing the number of sent messages over days or weeks, so that receiving servers can establish a reputation before you start bulk sending en masse. 

In order to use a custom domain, there are several steps that need to be completed.  

  • A custom submain needs to be configured, so that Feedback Loop Messaging can be received and processed.
  • DKIM and SPF records need to be created and published, so that your messaging passes DMARC.
  • IP Addresses need to be allocated.
  • IP Addresses and the domain need to be ‘warmed’.

In addition to these required steps, we also recommend several items to ensure that you are successful. 


  • Data Hygiene. Receiving servers have several ways to determine if you regularly clean and prune your sending list, removing recipients that have unsubscribed, as well as bad recipients and recipients that do not engage with your messaging.  Continuing to send messaging to a mailbox that does not engage with your messaging is a sure sign that you are not performing regular data hygiene and will quickly land you a bad reputation.     You should periodically prune your contact list, checking for spelling mistakes, typos, and removing recipients that either do not engage or have requested to unsubscribe.   CharityEngine offers a list cleaning service to assist with this task.
  • Domain Reputation Monitoring needs to be configured and subsequently monitored, to ensure that your reputation remains positive. There are several ways to monitor your domain reputation.  Each server, Google, Yahoo/AOL, Microsoft, Etc., offers their own console that needs to be configured and monitored for reputation changes.  CharityEngine offers Domain Reputation Monitoring as a service, in order to simplify this task. 
  • Opt-In/Double Opt-In Recipients. In general, sending messaging to recipients who haven’t positively indicated that they are interested in receiving your messaging is a sign of a bad domain, and most servers want to know that you abide by an opt-in or double opt-in system.   This means that either users have provided their email address and indicated that they are interested in receiving messaging, known as single opt-in, or that you have then taken that address and sent a message, allowing them to indicate that they want to continue receiving messaging, known as double opt-in.   CharityEngine offers a service that simplifies this process for you and allows your contacts to not only indicate their interest, but also to prune out disinterested recipients, ensuring your custom domain maintains a positive reputation. 


In the end, each configuration has its own advantages and disadvantages, and if you have questions about which route is best for you, the staff at CharityEngine are available to answer these questions and help you make an informed decision. 



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