What are best practices for deliverability when sending a first email campaign to an old list?

Key findings

• Risk of high bounce rates: Manually transcribed email addresses often contain typos, leading to invalid emails and subsequent hard bounces. A high bounce rate negatively impacts sender reputation.
• Forgotten consent: Subscribers on old lists may have forgotten giving consent, increasing the likelihood of spam complaints or simply not engaging with your emails.
• Sender reputation damage: High bounce rates, spam complaints, and low engagement signals (such as low open rates and click-through rates) can quickly tarnish your domain and IP reputation. Learn about recovering a damaged domain reputation.
• Spam trap risk: Older, uncleaned lists are more likely to contain spam traps, which are email addresses used by ISPs to identify senders of unsolicited mail, leading to immediate blocklisting.
• Blocklisting potential: Aggressive sending to an unverified old list can result in your sending IP or domain being added to a blocklist (or blacklist), preventing future emails from reaching their destination.

Key considerations

• Email verification: Before sending, use an email verification service to clean the list, identify invalid addresses, and remove potential spam traps. This is critical for improving deliverability, especially for old lists.
• Permission-based sending: Only send to recipients who have explicitly opted in and reasonably expect your emails. Consent degrades over time, so older sign-ups carry more risk.
• Re-engagement strategy: Consider a phased re-engagement campaign instead of a full blast. This involves sending to small segments, monitoring engagement, and gradually increasing volume. More insights on re-engaging stale subscribers.
• Gradual sending (warming up): If the list hasn't been used in a while, or if you're sending from a new domain, warm up your sending reputation by starting with small batches of highly engaged contacts and slowly increasing volume. This is especially true when warming up an old email list.
• Content and expectations: The first email should remind recipients how they signed up, reiterate the value proposition, and clearly explain how to opt out. Set clear expectations from the outset.

Key opinions

• Prioritize confirmed opt-in (COI): Marketers frequently suggest a confirmation email process. They say this should happen at the time of acquisition, or if not, it should be done now to ensure only confirmed addresses receive mail. This helps filter out typos and bots.
• Don't fear low opt-in rates: If people won't double opt-in, it might indicate they don't truly want your emails, which is a larger issue. Sending to unengaged contacts can harm your sender reputation.
• Time sensitivity for old lists: If sign-ups occurred more than a few months ago, subscribers may have forgotten, increasing the likelihood of spam complaints. It's advisable not to send to anyone who requested emails more than three months ago without re-confirmation.
• Gradual volume ramp-up: Avoid sending to the entire list at once. Instead, ramp up the volume gradually, starting with the newest or most engaged contacts to build trust with internet service providers (ISPs).
• Value proposition reminder: The first email to an old list should remind recipients why they signed up, reiterate the value, and clearly explain how to opt out.

Key considerations

• Double opt-in challenges: While ideal, confirmed opt-in can sometimes prevent genuinely interested subscribers from receiving emails, and the process itself can sometimes trigger spam filters. This highlights the ongoing debate around re-engaging inactive email subscribers.
• Avoiding spammer tactics: Sending small batches to bypass spam filters (or fixing emails going to spam) is a strategy commonly associated with spammers and can backfire by drawing unwanted attention from ISPs.
• Modern sign-up methods: Relying on physical sign-ups is outdated. QR codes or mobile forms are better alternatives to minimize transcription errors and enable immediate digital confirmation processes.
• Email verification services: These services can help identify invalid typos and reduce bounce rates, even if they don't fully address the consent issue. Always maintain proper IP allocation and authenticate your domain.
• Holistic list cleaning: Regularly cleaning your email list is a crucial ongoing best practice, not just for old lists. This involves removing inactive or unsubscribed contacts and known spam traps.

Key opinions

• Double opt-in as standard: Confirmed opt-in (COI) is generally considered the best practice to ensure explicit consent and reduce bounce rates and spam complaints, even if it might mean a slightly smaller list size.
• Risk of old data: Physical sign-ups often lead to typos, and consent expires over time. Sending to lists that are several months old without re-confirmation is a high-risk activity due to forgotten consent and increased spam complaints.
• Gradual volume is key: Sending gradually to an old list helps build a positive sending reputation with ISPs. Starting with smaller, more engaged segments can mitigate initial risks. Consider best practices for low sending volume.
• Spammer-like behavior: Attempting to send in small batches to bypass spam filters is a known tactic of malicious senders and will likely flag your sending behavior as suspicious, leading to worse deliverability.
• Double opt-in isn't always perfect: While recommended, some experts acknowledge that COI can be problematic, such as when blocklists or ISPs themselves click confirmation links, leading to false positives or listing issues.

Key considerations

• Consent decay: The older the list, the higher the chance that recipients have forgotten opting in or are no longer interested. This 'consent decay' significantly increases the risk of complaints.
• Sender reputation preservation: Protecting your sender reputation should be the top priority. A single bad campaign to an old list can inflict long-term damage, leading to emails consistently landing in spam folders or being blocked.
• Smart list segmentation: Segment your old list by recency of sign-up or known engagement. Target the most recently acquired and active subscribers first to test the waters and build positive signals.
• Monitoring metrics: Closely monitor your bounce rates, complaint rates, and engagement (opens, clicks) for these campaigns. High rates in any of these areas are immediate red flags and indicate a need to adjust your strategy. You can use Google Postmaster Tools to improve domain reputation.
• Proactive list cleaning: Regularly remove unengaged subscribers, hard bounces, and known spam traps to maintain list health and improve overall deliverability. This is part of how to prioritize email list cleaning.

Key findings

• List cleaning is mandatory: Documentation across platforms emphasizes that importing clean lists and conducting regular list cleaning are fundamental for improving email deliverability. This includes removing invalid addresses and unengaged subscribers.
• Opt-in importance: Send only to recipients who have explicitly opted-in. Purchased or outdated lists pose a significant risk to sender reputation and should be avoided or carefully managed with re-permissioning campaigns.
• Warming and ramping: For new sending domains or re-engaging old lists, gradual volume increases (warming and ramping) are recommended to build a positive sending history with ISPs. This helps establish sender reputation effectively.
• Authentication is critical: Authenticating your email domain with SPF, DKIM, and DMARC is a foundational step in email deliverability. It helps ISPs verify your identity and trust your emails. Learn about DMARC, SPF, and DKIM.

Key considerations

• Consistent sending cadence: Maintaining a consistent sending rate over time is crucial. Sudden large sends, especially to unengaged or old lists, can negatively impact your sender reputation, making it harder for future emails to be delivered. Klaviyo explains email deliverability practices.
• Content quality and relevance: Content should be personalized and relevant to the recipient. Avoiding spam trigger words in subject lines and body text is essential to bypass spam filters and improve engagement. Best practices for sending to disengaged lists.
• Monitor deliverability metrics: Regularly monitor your deliverability rate, bounce rate, complaint rate, and open/click rates. These metrics provide insights into your sender health and indicate areas for improvement.
• Mobile optimization: Ensure emails are mobile-optimized. A significant portion of emails are opened on mobile devices, and a poor mobile experience can lead to low engagement and increased unsubscribes.