How do subdomain deliverability issues affect parent domains, and what are the primary causes of email deliverability problems?
Summary
What email marketers say9Marketer opinions
Email marketer from NeilPatel.com shares that factors impacting email deliverability include sender reputation, email authentication (SPF, DKIM, DMARC), content quality, engagement rates, and blacklist status.
Email marketer from ActiveCampaign answers question about sender reputation. Sender reputation is so important to email deliverability, and it can be affected by many things.
Email marketer from Reddit explains that subdomains generally operate with some independence but mailbox providers use reputation of all parts of the domain for filtering decisions, including subdomains. So you can't hide behind a subdomain.
Email marketer from HubSpot explains that low engagement rates (opens, clicks) are a primary driver of deliverability issues. Mailbox providers use engagement to determine whether emails are wanted by recipients.
Email marketer from SendGrid explains that if a subdomain is sending spam, it can negatively impact the reputation of the parent domain. They recommend segmenting sending across different subdomains to isolate reputation issues.
Email marketer from Postmark shares that using subdomains for different types of email (transactional vs marketing) can help isolate reputation issues. If marketing emails have deliverability problems, it won't affect transactional emails sent from a separate subdomain.
Email marketer from GMass answers question about spam traps. If you email spam traps, inbox providers know you're up to no good.
Email marketer from Mailjet shares that it's important to maintain a good sender reputation on each subdomain because mailbox providers can associate bad practices with your overall brand if many subdomains have issues.
Email marketer from EmailToolTester shares that newer domains may have lower deliverability due to the lack of established reputation. Gradually increasing sending volume over time can help build a positive reputation.
What the experts say6Expert opinions
Expert from Email Geeks explains that only a half dozen public blocklists are widely used and affect delivery, while another dozen indicate some bad traffic.
Expert from Spam Resource explains that if you're using a shared IP address, your deliverability can be affected by other senders on that IP. They recommend monitoring your IP reputation and considering a dedicated IP if problems arise.
Expert from Word to the Wise explains that consistently sending email, even if it's a small volume, is better for your sender reputation and deliverability than sending large volumes infrequently.
Expert from Word to the Wise answers question about email content quality. It is important to make sure the content is what users want to see and do - and make it easy for them to do those things
Expert from Email Geeks explains that mailbox providers likely tie subdomains and root domains together at some level. While they mostly stand alone, significant problems can bleed across the root domain. Bad sending practices will eventually lead to issues with RBLs and mailbox providers.
Expert from Email Geeks explains that deliverability issues are not from DMARC policy or SPF lookups but from recipients interacting with mail in ways that suggest it is unwanted.
What the documentation says4Technical articles
Documentation from Google Workspace Admin Help explains that subdomains inherit some reputation from the parent domain, and poor sending practices on a subdomain can negatively impact the parent domain's reputation. They strongly recommend monitoring subdomain sending practices.
Documentation from DMARC.org explains that DMARC policies can be applied to subdomains via the 'sp' tag in the DMARC record, allowing organizations to set different policies for subdomains than the parent domain.
Documentation from ietf.org explains that SPF records should be created for subdomains that send mail to prevent spoofing. An empty SPF record (v=spf1 -all) should be set on subdomains which do not send emails.
Documentation from Microsoft answers question about email deliverability. It describes how to improve email deliverability for email marketers.