Summary
The increase in hard bounces from smaller domains is a multifaceted issue stemming from strict spam filtering and heightened sensitivity to various factors. Core issues include a compromised sender reputation (affected by spam complaints, low engagement, and potentially listing on blocklists), improper email authentication (SPF, DKIM, DMARC), and poor list hygiene. Sending IPs with ratios of spam to ham across different time windows, or new IPs without a proper warm-up, can also trigger blocks. Content-related problems, such as spammy signatures or the use of certain keywords, are also impactful, as are dramatic changes in sending volumes. Finally, discrepancies between visible and actual “From” addresses and exceeding the smaller sending limits used by some smaller domains are likely to lead to increased hard bounces. The use of SMTP error codes provides key information, and engagement metrics serve as a strong indicator.
Key findings
- Sender Reputation is Key: A damaged sender reputation, resulting from spam complaints, low engagement, or blocklisting, dramatically increases hard bounces, particularly from more sensitive smaller domains.
- Authentication is Essential: Incomplete or incorrect email authentication (SPF, DKIM, DMARC) causes smaller domains to reject messages outright, generating hard bounces.
- List Hygiene Matters: Sending emails to inactive or invalid addresses leads to bounces; smaller domains react more severely to this issue.
- IP Warm-up Critical: Lack of proper IP warm-up, especially after switching providers, results in many blocks from smaller ISPs.
- Content Triggers Exist: Certain keywords, phrases, or spammy signatures trigger spam filters more aggressively, leading to more bounces.
- Volume Spikes Harmful: Sudden increases in sending volume can be interpreted as spam, dramatically raising bounce rates.
- Engagement is Informative: Low engagement metrics (open rates, click-through rates) negatively affect deliverability, causing bounces from some domains.
- Domain Age matters: New domains can face deliverability challenges including increased bounces, as smaller domains tend to be cautious of unestablished senders.
Key considerations
- Monitor Reputation Constantly: Continuously monitor sender reputation using tools like Google Postmaster Tools and Sender Score to identify and address issues promptly.
- Maintain Pristine Lists: Regularly clean email lists by removing inactive and invalid addresses and implement double opt-in to ensure recipients are engaged.
- Implement Robust Authentication: Ensure SPF, DKIM, and DMARC are correctly configured to prove sender legitimacy and improve deliverability.
- Warm-Up IPs Methodically: Gradually warm up new IPs to establish a positive sending reputation before sending large volumes of emails.
- Review Content Diligently: Regularly review and update email content, avoiding spammy terms and signature practices.
- Ramp Up Volume Slowly: Gradually increase sending volume to establish a consistent sending pattern and avoid triggering spam filters.
- Manage Complaints Proactively: Actively manage spam complaints, investigating the causes and implementing measures to prevent future complaints.
- Monitor Sending Limits: Adhere to sending limits, especially when sending to smaller domains using services like Microsoft EOP and research limits for target domains.
- Monitor Engagement: Focus on strategies to improve engagement metrics by personalising emails and sending relevant content.
- New Domain Trust: If using new domains, prioritize building trust and a positive sending reputation over time to mitigate deliverability issues and adhere to best practices and guidelines.
What email marketers say
13 marketer opinions
An increase in hard bounces from smaller domains can stem from various factors, largely due to these domains often having stricter spam filters and lower tolerance for issues that larger ISPs might overlook. Common causes include poor sender reputation influenced by spam complaints, low engagement, and blocklist status. Issues with email authentication (SPF, DKIM, DMARC), sudden changes in sending volume, and a lack of IP warming can trigger these stricter filters. Discrepancies between visible and actual 'From' email addresses, spammy content, and outdated email lists also contribute to deliverability problems. Switching to a new email marketing provider without properly establishing a sending reputation, hitting spam traps or sending to invalid email addresses can also lead to higher bounce rates. Addressing these issues through proper email authentication, regular list cleaning, and careful monitoring of sender reputation can improve deliverability to smaller domains.
Key opinions
- Sender Reputation: Poor sender reputation, influenced by spam complaints and low engagement, leads to increased hard bounces, especially from smaller domains.
- List Hygiene: Sending to inactive or invalid email addresses results in hard bounces, with smaller domains having stricter spam filters.
- Email Authentication: Lack of proper email authentication (SPF, DKIM, DMARC) causes smaller domains to reject emails, leading to hard bounces.
- Sudden IP Changes: Switching to a new email marketing provider or IP without warming up can cause deliverability issues with smaller domains.
- Content Issues: Spammy keywords or phrases in email content can trigger spam filters, increasing hard bounce rates from smaller domains.
- Volume Changes: Sudden changes in sending volume can be interpreted as spam, resulting in higher hard bounce rates from smaller domains.
- Blocklist Status: Being on a blocklist, even a smaller one used by smaller ISPs, can cause an increase in bounces.
Key considerations
- Monitor Sender Reputation: Regularly monitor sender reputation to identify and address issues impacting deliverability to smaller domains.
- Clean Email Lists: Maintain a clean email list by removing inactive and invalid email addresses to reduce hard bounces.
- Implement Email Authentication: Ensure proper email authentication (SPF, DKIM, DMARC) to prove sender legitimacy and improve deliverability.
- Warm-Up IPs: Gradually warm up new IPs to establish a sending reputation before sending large volumes of emails.
- Content Review: Regularly review and update email content to avoid spammy terms and triggers.
- Gradual Sending: Gradually increase sending volume to establish a consistent sending pattern and avoid triggering spam filters.
- Monitor blocklists: Continuously monitor the status of your IP/Domain on blocklists.
Marketer view
Email marketer from Reddit shares that a sudden switch to a new email marketing provider can cause deliverability issues. Smaller domains may flag the new sending IP as suspicious, resulting in more hard bounces until the new IP establishes a reputation.
5 Oct 2023 - Reddit
Marketer view
Marketer from Email Geeks shares that one of the issues being picked up is the discrepancy between the visible From email (news@marchofdimes.org) and the actual From email (noreply@emails.marchofdimes.org), leading to spam reports.
24 Mar 2023 - Email Geeks
What the experts say
2 expert opinions
The increase in hard bounces from smaller domains can be attributed to two primary factors: damaged sender reputation and the use of new domains. Smaller domains are often more sensitive to sender reputation; poor engagement or high complaint rates can lead to increased bounces. Additionally, new domains face deliverability challenges because smaller domains are wary of unestablished senders. While domain age builds trust, new domains can still establish good sending reputations over time.
Key opinions
- Sender Reputation: Damaged sender reputation, stemming from low engagement or high complaint rates, is a significant cause of increased hard bounces from smaller domains.
- New Domains: New domains often face deliverability challenges and higher hard bounce rates, as smaller domains tend to be cautious of unestablished senders.
Key considerations
- Improve Sender Reputation: Focus on strategies to improve sender reputation, such as increasing engagement and reducing spam complaints, to enhance deliverability to smaller domains.
- Establish Domain Trust: For new domains, prioritize building trust and a positive sending reputation over time to mitigate deliverability issues.
Expert view
Expert from Spamresource shares that new domains often experience deliverability challenges, including increased hard bounces. Smaller domains are likely to be wary of new senders. Domain age helps to establish trust, but new domains can build good sending reputations.
22 Feb 2022 - Spamresource
Expert view
Expert from Word to the Wise explains that a damaged sender reputation is a primary cause of deliverability issues. Smaller domains might be more sensitive to reputation, resulting in increased hard bounces if sender reputation is poor due to low engagement or high complaint rates.
12 Aug 2021 - Word to the Wise
What the documentation says
4 technical articles
An increase in hard bounces from smaller domains can be attributed to several technical factors. Hard bounces, indicated by 5xx SMTP error codes, often signify permanent delivery failures due to invalid email addresses, non-existent domains, or recipient server rejection. Maintaining a good domain and IP reputation is critical, as is adhering to sending limits, which can be stricter for smaller domains using services like Microsoft EOP. Engagement metrics, such as open and click-through rates, also play a role; low engagement can signal unwanted emails and lead to increased filtering and hard bounces.
Key findings
- SMTP Errors: Hard bounces are indicated by 5xx SMTP errors, signaling permanent delivery failures.
- Reputation Importance: Maintaining a good domain and IP reputation is critical for avoiding hard bounces.
- Sending Limits: Exceeding sending limits, especially for smaller domains, can lead to temporary or permanent blocks and hard bounces.
- Engagement Metrics: Low engagement metrics (open rates, click-through rates) can lead to increased filtering and hard bounces, particularly from smaller domains.
Key considerations
- Monitor SMTP Errors: Monitor SMTP error codes to identify and address the root causes of hard bounces.
- Improve Reputation: Use tools like Google Postmaster Tools to monitor and improve domain and IP reputation.
- Adhere to Sending Limits: Adhere to sending limits, especially when sending to smaller domains using services like Microsoft EOP.
- Boost Engagement: Implement strategies to improve engagement metrics (open rates, click-through rates) to signal email relevance.
Technical article
Documentation from SparkPost explains that engagement metrics, such as open rates and click-through rates, are crucial for deliverability. Low engagement rates can signal to ISPs that emails are unwanted, leading to increased filtering and hard bounces, particularly from smaller domains.
18 Feb 2024 - SparkPost
Technical article
Documentation from Google explains that maintaining a good domain and IP reputation is critical for avoiding hard bounces. Google Postmaster Tools provides data on spam rate, IP reputation, and domain reputation, helping senders identify and address deliverability issues that can lead to bounces.
13 Feb 2024 - Google
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