Strategies for managing outbound email mailboxes

I had a call with Manny Adelstein to help with Clay's email infrastructure and this is what we talked about. Most people underbuild their outbound infrastructure. They buy 3–5 domains, warm them up, and hope deliverability holds. But if you’re serious about scale, that’s not enough. Here’s what we’ve learned running high-volume outbound: If you want to send 1,000 emails per day, you need the capacity to send 3,000. Why? Because domains burn. Even if your copy is clean and your targeting is perfect, some emails will hit spam. On average, a domain lasts ~2 months before you need to rotate it. So we use a three-set system: Set 1: actively sending Set 2: fully warmed and on deck Set 3: aging in the background When Set 1 gets tired, you switch to Set 2, start warming Set 4, and keep going. The machine never stops. Here’s the tip most people miss: buy domains early and let them age. Even if you’re not using them yet, aging them means when you need new inboxes, you’re not starting from scratch with a zero-trust domain. We buy hundreds (sometimes thousands) of domains when there are sales. Right now, Dynadot is running a promo: .coms for $7 and .cos for $2. We’ll grab thousands and let them sit—no inbox cost until we need them. Use Zapmail.ai and Hypertide.io for inbox setup. They give you admin access, don’t mix your domains with shady senders, and plug right into SmartLead. Don’t wait until deliverability drops to prepare. Stockpile aged domains now, and you’ll always be ready to scale or recover—without missing a beat. I know some people will say, "If you send good emails, you don't need to do this." We just had someone with literally an 8% reply rate which 80% of them being positive go from an 8% reply rate to 1% because of people still marking them as spam. I wish it wasn't this way either, but this is just what we have seen that we have to do.

After reviewing data from 1,000s of inboxes at RevGrowth, these 8 practices have made the biggest impact for consistent 99% email deliverability:   Most teams skip at least one of these, then wonder why their cold emails land in spam.   Here's what we do:   1. Use Secondary Domains - Never send from your main domain > We buy secondary domains through Porkbun for cheap, easy management   2. Track Replies Only - Open and click tracking hurt deliverability > I keep reply tracking on and turn everything else off. Clean signal, less risk   3. Send Fewer Emails Per Mailbox - I stick to 30 emails/day per mailbox, max > Spread your volume across several domains. Fewer red flags, more consistency   4. Warm Up Slowly - Ramp up sending volume over time. > Start low, increase gradually. This builds trust with inbox providers.   5. Double-Verify Your Lists - Bad data kills sender reputation > We use LeadMagic, Icypeas, and Prospeo.io for email search, then verify with LeadMagic. Clean lists = low bounce rates   6. Use Modern Sending Platforms - Old-school SEPs drag down deliverability > I recommend EmailBison or Smartlead   7. Automate CRM Syncing - Manual updates cause errors and missed follow-ups. > OutboundSync handles real-time syncing with HubSpot or Salesforce. Less manual work, more accuracy.   8. Stick to Plain Text - Links and images lower inbox rates. > I write text-only emails. They look more human and get better placement.   Our team applies these 8 steps in every workflow ourselves & all client accounts.   What’s been your biggest deliverability challenge lately?

One of the most common pain points I hear from GTM leaders is that their outbound emails are going to spam. Good news. This is easily avoidable. At Unify, our customers send tens of thousands of emails per month with no deliverability issues. Here are the 7 best practices I’d recommend for ramping up outbound email and avoiding spam/deliverability issues: 1) Email prospects who actually want to hear from you. This should go without saying, but you need to email people who could benefit from your product. If you start just spamming people who have no use for your product, never will, et cetera, you're setting yourself up for email deliverability issues. Even if you technically “could” do it, spray and pray will not deliver results. 2) Use multiple mailboxes per sender. You’ll want to have multiple mailboxes per sender. How many? Best practice here is to have anywhere between 5-10. This inbox count is usually safe to keep sends per inbox at a reasonable level. 3) Send emails from non-core domains. It’s important to have several domains that you can deliver emails from. We send most of our volume through unifygtm.io and unifygtm.co. While we also send outbound emails from unifygtm.com, having alternative domains spreads out the volume and keeps our core domain safe. 4) Warm your inboxes Using a warm-up service will simulate healthy conversation between different mailboxes. You should warm your inboxes for 45-60 days before sending real emails through them. Pro-tip: If you run into deliverability issues as you ramp up your outbound email motion, turn warming back on to improve deliverability health. 5) Nail your IP address setup. You’ll want to send from Non-Gmail IPs. Moving sends to a platform like Sendgrid or Unify managed IPs keeps your deliverability in check. IP addresses are as important as the domain that you deliver from. 6) Keep Volume Reasonable In 2024 it’s important to keep send volume per mailbox reasonable. My current recommendation: Keep your volume of sends between 50-75 a day. If you do need more, then create additional mailboxes. 7) Personalize Emails 1:1 Please, make sure you’re not sending the same generic message over and over. This is an easy way to get picked up as spam by ISPs. Prospects expect a personalized experience, and your outbound will perform better if it is truly personalized (this can be fully automated btw—but that’s a topic for a different post). Question for anyone else deep in email deliverability: what else would you add to this list? Anything I’m missing here? Let me know in the comments.