Our organization currently uses a dedicated IP address to manage our email sends, which total several hundred thousand daily outbound.
Generally speaking, about half of our send volume is from regular, daily newsletters to a well-maintained list. The other half is from more ad-hoc messaging like fundraising appeals or special communications that go to a wider, less maintained (and potentially riskier) universe of prospects. Messages in each group go out under two separate brand names.
We have secured a second dedicated IP address with the decommissioning of another business unit, and we hope to use this to bolster our deliverability.
So: What's the best way to go about using the second IP to boost deliverability?
We've heard several different theories on how to allocate sends, and have no idea which might be correct:
- Use one IP for the regular newsletters, and the other for ad-hoc messages. Assumed effects: the newsletter IP has high deliverability, while the ad-hoc IP is weaker; the ad-hoc emails don't harm deliverability for the newsletters, but the newsletters' better reputation doesn't bolster the ad-hoc.
- Use one IP for active subscribers, the other for lapsed reactivation. Assumed effects: the active IP has high deliverability, while the lapsed IP is weaker. Does this approach require us to vary the messaging we send to each group? What's the best way to achieve that segmentation in Marketo?
- Use one IP for each brand. Assumed effects: a wash, since the ad-hoc and regular newsletters are fairly evenly distributed across each brand.
What do you think? Is one of these the best option? Are there unanticipated pitfalls to either approach? Or is there another approach we should consider?