Summary
Sharing a sending domain with a partner is widely recognized as a significant risk to email deliverability and sender reputation. Both experts and documentation emphasize that a partner's poor sending practices, including spammy behavior, can negatively impact your domain's reputation, leading to blacklisting and reduced deliverability, regardless of your own efforts. This is because email providers and security protocols often consider the overall domain reputation, not just individual sender behavior. Using a dedicated sending domain is strongly recommended to maintain a positive reputation and protect your ability to reach recipients' inboxes.
Key findings
- Shared Reputation Risk: Sharing a domain means sharing its reputation, making you vulnerable to the negative impact of a partner's actions.
- Domain-Wide Impact: A primary domain's reputation directly affects all subdomains and associated senders, regardless of their sending practices.
- Blacklisting Threat: Poor sending practices from a partner can lead to blacklisting, harming the deliverability of all users sharing the domain.
- Best Practice Recommendation: Using a dedicated sending domain is crucial for maintaining control over your reputation and ensuring reliable deliverability.
Key considerations
- Avoid Shared Domains: Prioritize using a dedicated sending domain to minimize the risks associated with shared reputations.
- Monitor Partner Practices: If sharing is unavoidable, closely monitor your partner's sending practices and ensure they adhere to email marketing best practices.
- Domain Authentication: Implement domain authentication protocols (SPF, DKIM, DMARC) to enhance sender credibility and improve deliverability.
- Reputation Monitoring: Regularly monitor your domain reputation using tools like Google Postmaster Tools and Sender Score to identify and address potential issues promptly.
What email marketers say
10 marketer opinions
Sharing a sending domain with a partner introduces significant risks to email deliverability. A primary domain's reputation directly affects all associated subdomains and senders. Poor sending practices by one partner can lead to blacklisting and negatively impact the deliverability of others, even if they adhere to best practices. Experts recommend using dedicated sending domains and actively monitoring domain reputation to protect email performance.
Key opinions
- Reputation Impact: A poor primary domain reputation negatively affects all subdomains and associated sending addresses.
- Blacklisting Risk: Partner's poor sending practices can lead to blacklisting, impacting your deliverability.
- Shared Risk: Sharing a domain means your reputation is tied to the sending practices of others.
- Dedicated Domains: Using dedicated sending domains is crucial for maintaining a positive sender reputation.
Key considerations
- Monitor Reputation: Actively monitor your domain reputation to identify and address issues promptly.
- Authentication: Implement domain authentication to improve sender credibility.
- Sending Practices: Ensure all partners follow email marketing best practices.
- Dedicated IP: Consider using a dedicated IP address for greater control over your sending reputation.
Marketer view
Email marketer from Email Marketing Forum explains that sharing a domain with a partner can lead to blacklisting issues. If your partner engages in spam or poor sending practices, your emails may also be marked as spam due to the shared domain reputation.
30 May 2025 - Email Marketing Forum
Marketer view
Email marketer from StackExchange shares that shared sending infrastructure, including domains, can lead to deliverability problems if one user is blacklisted. It's essential to isolate sending activities to protect your reputation and ensure reliable delivery.
13 Feb 2022 - StackExchange
What the experts say
3 expert opinions
Sharing a sending domain with a partner poses significant risks to email deliverability and sender reputation. All experts agree that a partner's sending practices can negatively impact your domain reputation, potentially leading to blacklisting and compromised deliverability. Sharing domains should be avoided altogether to prevent potential damage.
Key opinions
- Shared Reputation: Sharing a parent domain means sharing email reputation, which introduces significant risks.
- Negative Impact: Partner's spammy behavior negatively impacts your domain reputation and deliverability.
- Compromised Deliverability: A compromised domain leads to problems with deliverability and sender reputation.
- Direct Impact: Actions of your partners directly affect your ability to reach recipients' inboxes.
Key considerations
- Avoid Sharing: Avoid sharing sending domains altogether to prevent potential damage.
- Monitor Practices: Closely monitor your partner's sending practices if sharing is unavoidable.
- Dedicated Domains: Opt for dedicated sending domains for better control over reputation.
- Security: Implement security measures to prevent domain compromise.
Expert view
Expert from Email Geeks explains that if you’re using the same parent domain you’re going to be sharing email reputation and you absolutely should not share sending domains at all because that’s going to break a lot of things.
14 Oct 2024 - Email Geeks
Expert view
Expert from Word to the Wise explains that a compromised domain can lead to serious problems with deliverability and sender reputation. If you share sending domains, the actions of your partners directly impact your ability to reach your recipients' inboxes.
11 Oct 2023 - Word to the Wise
What the documentation says
4 technical articles
Sharing a sending domain with partners can significantly harm your sender reputation and email deliverability. Documentation from multiple sources, including Google, Microsoft, RFC, and Auth0, emphasizes that poor email practices from one partner can lead to your emails being marked as spam or blocked, regardless of your own sending practices. The overall domain reputation, not just individual sender behavior, is taken into account by email providers and security protocols. Therefore, a custom, dedicated domain is always preferred to protect your reputation.
Key findings
- Reputation Dilution: Sharing a domain dilutes sender reputation due to poor practices of partners.
- Spam Marking: Emails can be marked as spam or blocked, even with good sending practices.
- Overall Reputation: Email providers consider the overall domain reputation, not just individual senders.
- Security Risks: Poor partner security implementation can open the door to reputation damage.
Key considerations
- Monitor Practices: Closely monitor the email practices of any partners sharing your domain.
- Control Access: Carefully control who has access to share your sending domain.
- Dedicated Domain: Implement a custom and dedicated domain for sending emails to isolate and protect reputation.
- Security Protocols: Ensure strong security measures are in place to protect domain integrity.
Technical article
Documentation from Auth0 describes that the issue with using a shared domain as part of email deliverability is it opens the door to domain reputation issues from others, and that a custom domain should always be implemented.
21 Dec 2021 - Auth0
Technical article
Documentation from RFC outlines that domain name system security needs to be strictly monitored. Any partner who damages this can damage your own reputation and how the internet sees you.
5 Sep 2022 - RFC Editor
Are custom sending domains worth the money and effort?
Can I use the same sending domain with multiple ESPs?
How do shared IP pools and sending domains impact email sender reputation for ESPs?
How do subdomain deliverability issues affect parent domains, and what are the primary causes of email deliverability problems?
How does parent domain reputation affect subdomain deliverability and sender reputation?
How does primary domain authentication affect subdomain deliverability and compliance?
