Switching to a new custom sending domain resets your sender reputation to zero, like a new credit score. You must gradually ramp up sending volume, starting with your most engaged subscribers first, to build a positive history with mailbox providers.

The risk of high-volume, "spray and pray" outreach extends beyond poor response rates. It actively damages your company's domain reputation. Email providers will flag your entire domain (e.g., yourcompany.com) as spam, tanking deliverability for everyone in the organization, not just the individual seller.

Sending more often (e.g., from weekly to daily) amplifies engagement signals for mailbox providers. If a segment of your list is unengaged, you are now sending more frequent negative signals. To counteract this, you must tighten your list hygiene rules.

Email providers prioritize senders with high engagement. Sending at least five emails per month generates more opens and clicks, signaling credibility. This counterintuitively leads to higher average open rates and better inbox placement, contrary to the common fear of over-sending.

If your sending practices tarnish your reputation, your Email Service Provider (ESP) may move you to a lower-tier shared IP address without your knowledge. This is done to protect their high-quality IPs, but it will severely harm your future deliverability, creating a downward spiral that is difficult to escape.

Contrary to the fear of over-sending, emailing at least five times per month improves deliverability. Email providers view consistent recipient engagement (opens, clicks) as a sign of a credible sender, leading to better inbox placement and significantly higher open rates.

Email providers heavily weigh engagement signals (replies, opens, clicks) within the first week of a new subscription. This initial "probation period" has a disproportionate impact on your long-term sender reputation and deliverability. A welcome sequence should be engineered to maximize these signals in a compressed timeframe.

Historically, an ESP's reputation heavily influenced deliverability. Now, with sender authentication requirements from Gmail and Yahoo, reputation is tied directly to your sending domain. This means your reputation follows you between ESPs, and you are solely responsible for managing it.

Smaller senders (<5,000 subscribers) struggle to build a stable domain reputation due to low volume where a few spam complaints have an outsized impact. It's often better to leverage the established reputation of your ESP's domain until you have enough volume to manage your own.