How does one customer's DKIM signature affect other customers' deliverability?

Email marketer from Email Geeks shares that if there are lots of bad senders, they may give your domain a bad reputation, which will apply to all with that domain. If not, you're probably fine as-is, but that can always change.

Email marketer from SparkPost shares that while DKIM helps authenticate emails, a sender's reputation also plays a crucial role in deliverability. If a customer shares a DKIM signature and engages in poor sending practices, it can negatively impact the reputation and deliverability of other customers sharing the same signature.

Email marketer from Mailosaur shares that a DKIM record proves your emails are genuine and haven't been tampered with. Without proper DKIM setup, your emails are more likely to end up in spam. Sharing DKIM can be risky as the behavior of one sender impacts the reputation of all.

Email marketer from StackExchange explains that using a single DKIM key for multiple customers creates a single point of failure. A compromised account or poor sending practices from one customer can negatively impact the deliverability of all other customers using the same DKIM signature.

Email marketer from Mailjet explains that in shared IP environments, the sending practices of one customer can affect the deliverability of others. While DKIM authenticates the message content and sender, a poor sending reputation associated with the shared IP can still impact deliverability.

Email marketer from GMass explains the importance of setting up sender authentication like DKIM. A positive reputation builds trust with mailbox providers which will help your emails land in the inbox. Shared DKIM keys mean shared reputations, so the bad behavior of one sender impacts all.

Email marketer from Reddit explains that if you're sharing a DKIM key across multiple clients or domains, one bad actor can ruin it for everyone. ISPs will see the shared DKIM signature as a single entity, and if one sender gets blacklisted, everyone using that signature suffers.

Email marketer from SendGrid explains that sender reputation is a critical factor in email deliverability. When using shared sending infrastructure, the actions of one customer can affect the reputation of the entire shared environment, potentially impacting the deliverability of other customers. DKIM helps to verify email authenticity, but it doesn't completely mitigate the risks associated with a poor sending reputation.

Email marketer from Email on Acid explains that your sending reputation is like your credit score. Bad sending practices (like spamming) lower your score, while good practices (like engaging content) raise it. Shared IPs mean shared reputations, so one bad sender can hurt everyone.

Expert from Email Geeks shares that signing with your own key as well as your customers' keys (or just your customers') is a choice. Signing with your own key makes things easier, and if your customers are generally good, it may help with delivery, especially when onboarding new customers.

Expert from Email Geeks explains that DKIM provides an identifier for an entity taking responsibility for the email. If some customers send unwanted mail, it reflects badly on the DKIM signing entity and its other customers.

Expert from Word to the Wise explains that proper DKIM authentication is critical. If one customer's DKIM setup is faulty or misused, it can lead to deliverability problems for all users sharing the same infrastructure or DKIM key, especially if they all operate under the same organizational domain.

Expert from Spam Resource explains that with shared sending infrastructure, such as ESPs providing services to multiple customers, the reputation of one customer can affect others. If one customer engages in spammy practices, it can negatively impact the shared IP address or domain reputation, affecting deliverability for all customers using that infrastructure, regardless of DKIM.

Expert from Email Geeks explains a mail stream identifier is anything used to identify mail from a particular sender, explicitly DKIM d= values and IP addresses, implicitly anything an MBP uses to predict mail quality based on past mail.

Documentation from Microsoft Learn explains that implementing SPF, DKIM, and DMARC helps ensure that recipient email systems trust messages sent from your domain. In a shared environment, if one customer fails to properly implement these, it can affect the reputation of the shared sending infrastructure, impacting other users' deliverability.

Documentation from Google Workspace Admin Help explains that DKIM helps prevent spoofing by verifying the domain from which an email is sent. When one customer's DKIM is compromised or misused, it can negatively affect the sending reputation of the shared infrastructure, impacting other customers.

Documentation from AuthSMTP explains that SPF, DKIM & DMARC work together to ensure email authenticity. If one domain's DKIM is compromised in a shared sending environment, it can impact the overall deliverability reputation of that shared environment, affecting all senders.

Documentation from RFC Editor explains that sharing a DKIM key across multiple domains or customers can lead to reputation issues. If one entity using the key engages in poor sending practices, it can negatively impact the reputation of all others using the same key.