Help ensure your emails
hit the inbox
Stop guessing why your messages end up in spam. Follow this 26-point checklist to achieve technical compliance, enhanced sender reputation, and delivery success.
Avoid Domain-Based Sorting
With mailing lists, avoid sorting or batching recipients by email domain (for example, grouping all @gmail.com or @yahoo.com addresses together). Sending large numbers of messages to the same mailbox provider in rapid succession can create short-term volume spikes, even if overall sending volume remains moderate.
Many mailbox providers monitor not only total traffic, but also per-domain and per-minute sending patterns. Concentrated delivery to a single provider may resemble automated or abusive activity and can lead to temporary throttling, deferred messages, or reputation impact.
To maintain smoother traffic profiles, mailing lists should be randomized or evenly interleaved across domains. This helps distribute delivery more naturally over time, reducing provider-specific spikes and supporting more stable inbox placement.
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