Modern antispam systems are sophisticated, often knowing far more about your domain and sending patterns than you might expect. They monitor not only the content and authentication (SPF/DKIM/DMARC) of your emails but also the consistency of your sending behavior. A sudden deviation in these patterns can lead to significant delivery issues, even if your emails are properly authenticated.
Understanding the Risks of Sudden Volume Increases
Consider this scenario : your domain has been sending 10,000 emails per day for years through a single platform. If you suddenly switch to a new platform and increase your email volume to 100,000 emails in one day—even with DMARC, SPF, and DKIM properly configured—there’s a high likelihood that antispam filters will flag your domain’s activity as suspicious. This can result in delays or outright rejection of your emails.
For some types of email, such delays may not be critical. For example, delay with urgent communications, such as one-time passwords (OTPs) that customers need to access your platform, can lead to a poor user experience and potential business losses.
Best Practices for Managing Email Sending Patterns
To minimize the risks associated with changes in email volume and sending platforms, follow these best practices:
1. Segregate Sending Sources by Subdomain
Each type of email communication should have its own dedicated subdomain:
- Marketing emails: Use a marketing subdomain (e.g., marketing.yourdomain.com).
- Transactional invoicing emails : Use an invoicing subdomain (e.g., billing.yourdomain.com).
- OTP or authentication emails: Use a secure subdomain for authentication purposes (e.g., auth.yourdomain.com).
This separation helps ensure that delivery issues with one type of email do not impact others.
2. Gradual Scaling of Email Volume
When increasing the number of emails you send, do so gradually to avoid triggering antispam alarms. A safe approach is to increase the volume by approximately 15% per day. This gradual increase allows mailbox providers to adjust to your new sending pattern.
Use email analysis tools to detect anomalies in your sending patterns, such as unexpected peaks in volume or delivery errors. These insights can help you address potential problems before they impact your domain’s reputation.
Failing to follow these practices can lead to widespread email delivery issues. For example, if your marketing team sends a peak volume of emails without proper planning, major providers like Gmail, Yahoo, and even smaller local providers (e.g., Free, SFR, and Orange in France) may delay or block all emails sent from your domain. This could disrupt critical communications and harm your domain’s reputation.
Below is a screenshot from an email analysis tool, illustrating a peak in email volume followed by an immediate spike in delivery errors. This example highlights the importance of maintaining consistent sending behavior to avoid such issues.
By understanding how antispam systems monitor email domains and adopting these best practices, you can ensure reliable delivery of your emails, protect your domain’s reputation, and maintain trust with your recipients.