How should I handle `do_not_send`, `catch_all`, and `unknown` results from email verification APIs in my signup form?
Summary
What email marketers say10Marketer opinions
Email marketer from Stack Overflow shares to immediately reject invalid email addresses to reduce bounces and protect sender reputation. Suggests using client-side and server-side validation.
Email marketer from Validity Knowledge Base explains that catch-all domains can accept all emails sent to them regardless of mailbox existence. They suggest careful monitoring of these addresses due to the risk of spam traps and low engagement.
Email marketer from NeverBounce explains that 'do_not_send' results indicate addresses that are invalid, disposable, or role-based and recommends removing them from your mailing list to protect your sender reputation.
Email marketer from Reddit shares to segment catch-all addresses and monitor their engagement closely, and consider offering incentives for those users to provide a more specific email address.
Email marketer from EmailToolTester suggests removing 'do_not_send' emails immediately, as they are likely invalid and can harm your sender reputation.
Email marketer from Email Geeks shares proceed with caution advice, suggesting to slow and monitor activity. Addresses that may have a lower threshold for removing if not engaged. Suggests Confirmation of Intent (COI), and Captcha to protect forms from bots.
Email marketer from Gmass explains to segment and monitor catch-all addresses. If there is no engagement they suggest removing catch-all email addresses.
Email marketer from Medium article explains that 'unknown' results typically require a retry or further investigation, as the initial check couldn't confirm the address's validity. Suggests to retry and use double opt-in.
Email marketer from Email Hippo explains that an 'unknown' result from email verification usually means the server couldn't be reached or didn't provide a definitive answer in the given timeframe. They advise retrying unknowns and implementing a double opt-in process.
Email marketer from ZeroBounce explains that their email verification returns statuses like valid, invalid, catch-all, disposable, and unknown. They advise carefully managing catch-all addresses and immediately removing invalid ones.
What the experts say4Expert opinions
Expert from Email Geeks shares a GitHub list of disposable email domains and describes a past strategy of quietly suppressing addresses from those domains when relationship-building was the goal.
Expert from Word to the Wise explains that with catch-all addresses, it is important to implement strategies to filter for invalid addresses and maintain deliverability. Suggests further analysis.
Expert from Email Geeks expresses irritation when their catch-all email address is rejected, even though it's valid and deliverable.
Expert from Spam Resource explains it is important to consider factors such as deliverability, data quality, and legal compliance. Explains how to correctly validate.
What the documentation says4Technical articles
Documentation from Mailgun details that the Mailgun Email Verification API provides statuses like 'deliverable', 'undeliverable', 'risky', and 'unknown'. For 'risky' addresses, they suggest proceeding with caution and monitoring engagement. They recommend not sending to 'undeliverable' addresses.
Documentation from Kickbox clarifies that their service provides detailed result codes, including information about disposable emails, accept-all addresses, and invalid syntax. They suggest using this information to segment lists and tailor sending strategies.
Documentation from RFC explains technical specifications for email address syntax, and validation.
Documentation from Abstract API details that their API returns statuses such as 'valid', 'invalid', 'risky', and 'unknown'. They suggest treating 'risky' addresses with caution and implementing additional verification steps, such as a confirmation email.