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Comment by pembrook | Hacker News Reader

The site recommends a dedicated IP for people sending 50,000 emails per month, but this number is way lower than what I’ve heard from experts before.

I was told anything under 500,000+ emails per month and you might actually get worse deliverability from a dedicated IP vs. a shared IP at one of the big ESPs like mailchimp…since inbox providers like gmail/outlook see low volume IPs as suspicious (no idea why).

I’ve also heard your domain reputation is far more important than shared vs. dedicated IP at your ESP of choice.

Anybody know which advice is true?

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Unfortunately I've seen the complete opposite. We've had to purchase dedicated sending IPs for some of our clients that maybe send 50 emails a week.

Why? Because these emails are super important transactional notifications and we constantly saw stuff getting blocked on shared IPs. It would work fine for a while then get RBLd causing major major issues.

Sendgrid, sparkpost etc support all said the only solution was a dedicated IP with them. This does seem to work FWIW, but it's probably working out the same cost per send as sending a physical letter at this point!

You work in this field I gather? What do you think of the checklist? Do I need to add, correct or change anything?

>I’ve also heard your domain reputation is far more important than shared vs. dedicated IP at your ESP of choice.

For me the IP address has been the only significant factor in my email deliverability. I.e., emails sent from my mail server couldn't reach Outlook inboxes or even spam boxes. Straight-up silently rejected every time. If you look at the Outlook.com Smart Network Data Services (SNDS)[0], the terminology used is all about IP. That problem was resolved through a support ticket requesting a kind conditional white-listing.

That's been my experience so far, from the perspective of a low volume, personal email only. YMMV.

[0] https://sendersupport.olc.protection.outlook.com/snds/

There's no way to know, Google and the other big inbox providers don't reveal exactly how they do spam scoring, to avoid spammers from gaming it. You would hope they are using heuristics like domain reputation and email content over IP address reputation.

That being said if you send from a new or rarely used IP, every inbox provider will greylist you at a minimum, which causes delays.

True, which is why it's important to "warm up" your IP and slowly ramp up volume over time.

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