u/localspermseller

I run cold email for a B2B agency (targets are agencies/SaaS/automation shops — so mostly Google Workspace inboxes). I've burned two full batches of domains the exact same way and can't isolate the root cause. Would love a second set of eyes. (Disclosure, this is written by Claude; I had it write the post to collect all the data, tests, and progress I made with figuring out deliverability so I don't miss anything, i want to make a genuine service that helps businesses get more clients, but dealing with email deliverability is so disheartening, especially if you don't have a lot of capital, so i made this post detailing all ive tested and symptoms with the hopes of diagnosing the problem and have mailboxes survive atleast the first 2 weeks of sending)

Setup

• Smartlead, Google Workspace mailboxes, domains + mailboxes from InboxKit, 5 mailboxes/domain
• De-clustered domain names (not obvious cousin variants). All redirect to my real company site → Calendly (temporary while i make a vsl and get more proof of work with clients)
• Copy: plain text, name-only signature, no links/images in email 1, spintax + AI icebreakers, tracking off, randomized sends, 3-min gaps
• Warmup: Batch 1 = fresh, 2 weeks Smartlead warmup. Batch 2 = pre-warmed 4 weeks. Warmup left on. Ramp 5→10/day, in 5 increments every week
• Lists: Sales Nav → AnyMailFinder → Bouncer-verified, Google inboxes only. Bounce rate 0.4–1.5%

What happens (identical both batches)

• Domains land on SURBL (ABUSE) within week 1 (with the exception of 1 domain per batch, those domains always stay healthy while the others die)
• Everything looks fine for ~2 weeks: 15% reply rate, 60% positive, warmup health 90–100%
• Then warmup health collapses almost in 1 day to 80% then goes down day by day. Inbox placement test to fresh seeds: SURBL-listed domains hit 0/10 inbox, 10/10 spam. Dead

What I've tested / ruled out

• SPF/DKIM/DMARC all pass, mail-tester 9–10/10
• Per-domain SURBL check maps 1:1 — listed domains = 100% spam/dead; the one un-listed domain in each batch survives
• Redirect target (my own domain) is clean on SURBL, so they're not inheriting the listing from it
• Bounce rates are low, so lists aren't full of dead addresses
• Same copy AND same lists went to the survivor too
• Warmup health score is worthless as a signal if below 98%, one domain read 96% warmup while landing 100% spam on real seeds
• When the first batch died, I tried getting 4-week warmed mailboxes instead of 2 yet it's the same story

The part I can't explain — mirror-image audience split

• My aged brand domain (sent the exact same lists, same volume, never burned): inbox on Workspace, spam on consumer Gmail
• The fresh survivor: inbox on Google Workspace, spam on normal Gmail accounts (which isn't a big deal because all my lists consist of Google Workspace)

My thoughts

1. Pristine spam traps in the "verified" lists (Bouncer/AnyMailFinder can't catch live traps; pattern-guessed emails are risky) — whichever domain's slice hits a trap gets SURBL-listed and dies first
2. Age/legitimacy is the real survival factor; fresh domains never earn Workspace trust through warmup alone

Questions
Why do fresh domains keep getting SURBL-AB listed within a week even off verified lists? I've read that being blacklisted by SURBL is only the symptom of deliverability, not the problem, so what could be the main issue causing it? why do all my domains die with the exception of 1 every time? if its spam traps that are causing this, what can you do to avoid them?

(Disclosure, this is written by Claude; I had it write the post to collect all the data, tests, and progress I made with figuring out deliverability so I don't miss anything, i want to make a genuine service that helps businesses get more clients, but dealing with email deliverability is so disheartening, especially if you don't have a lot of capital, so i made this post detailing all ive tested and symptoms with the hopes of diagnosing the problem and have mailboxes survive atleast the first 2 weeks of sending)

I run cold email for a B2B agency (targets are agencies/SaaS/automation shops — so mostly Google Workspace inboxes). I've burned two full batches of domains the exact same way and can't isolate the root cause. Would love a second set of eyes.

Setup

• Smartlead, Google Workspace mailboxes, domains + mailboxes from InboxKit, 5 mailboxes/domain
• De-clustered domain names (not obvious cousin variants). All redirect to my real company site → Calendly (temporary while i make a vsl and get more proof of work with clients)
• Copy: plain text, name-only signature, no links/images in email 1, spintax + AI icebreakers, tracking off, randomized sends, 3-min gaps
• Warmup: Batch 1 = fresh, 2 weeks Smartlead warmup. Batch 2 = pre-warmed 4 weeks. Warmup left on. Ramp 5→10/day, in 5 increments every week
• Lists: Sales Nav → AnyMailFinder → Bouncer-verified, Google inboxes only. Bounce rate 0.4–1.5%

What happens (identical both batches)

• Domains land on SURBL (ABUSE) within week 1 (with the exception of 1 domain per batch, those domains always stay healthy while the others die)
• Everything looks fine for ~2 weeks: 15% reply rate, 60% positive, warmup health 90–100%
• Then warmup health collapses almost in 1 day to 80% then goes down day by day. Inbox placement test to fresh seeds: SURBL-listed domains hit 0/10 inbox, 10/10 spam. Dead

What I've tested / ruled out

• SPF/DKIM/DMARC all pass, mail-tester 9–10/10
• Per-domain SURBL check maps 1:1 — listed domains = 100% spam/dead; the one un-listed domain in each batch survives
• Redirect target (my own domain) is clean on SURBL, so they're not inheriting the listing from it
• Bounce rates are low, so lists aren't full of dead addresses
• Same copy AND same lists went to the survivor too
• Warmup health score is worthless as a signal if below 98%, one domain read 96% warmup while landing 100% spam on real seeds
• When the first batch died, I tried getting 4-week warmed mailboxes instead of 2 yet it's the same story

The part I can't explain — mirror-image audience split

• My aged brand domain (sent the exact same lists, same volume, never burned): inbox on Workspace, spam on consumer Gmail
• The fresh survivor: inbox on Google Workspace, spam on normal Gmail accounts (which isn't a big deal because all my lists consist of Google Workspace)

My theories

1. Pristine spam traps in the "verified" lists (Bouncer/AnyMailFinder can't catch live traps; pattern-guessed emails are risky) — whichever domain's slice hits a trap gets SURBL-listed and dies first
2. Age/legitimacy is the real survival factor; fresh domains never earn Workspace trust through warmup alone

Questions
Why do fresh domains keep getting SURBL-AB listed within a week even off verified lists? I've read that being blacklisted by SURBL is only the symptom of deliverability, not the problem, so what could be the main issue causing it? why do all my domains die with the exception of 1 every time? if its spam traps that are causing this, what can you do to avoid them?

As the title says, for weeks I have been running a few mailboxes on a good-performing campaign, getting positive replies, booking calls, same list-building steps, bounce rates around 1.5-0.5%, and then out of nowhere, in a few hours today, all the mailboxes on the campaign tank in warm up reputation, not my by much (from 100% for weeks to 89% in a few hours).

That might look like a good sign because of how small the drop is, but from my experience it's usually the beginning of the end for the fleet. What I want to find out is what could have caused this. Have you guys run into similar situations?

I use InboxKit for domains and mailboxes with their InfraGuard (which coincidentally I bought today, which is the same day the mailboxes tanked, but idk how it would be responsible), Smartlead for sending, Sales Nav, and Bouncer for leads and email validation

(Updated) Hello, as the title says, I keep buying new domains and mailboxes just for them to get burned 3weeks to a month in.

I use inboxkit to buy the mailboxes and smartlead for sending and warm up, I use sales nav for leads, anymailfinder for emails, bouncer for email verification, my bounce rates are below 2% most of the time around 1%, i use deep ai personalization for emails so each one is unique with a small template for cta, i get around 3-6% reply rates for the first 2 weeks.

yet after a week or 2 of sending 5-10 emails per mailbox a day (after the initial 2 weeks of warm up) i find that my warm up reputation tanks to 50-60% on smartlead, which usually means 60-90% of emails are landing in spam, i tried figure out this keeps happening to every mailbox i buy but to no avail.

The only progress I made is that my main domain for my company which is older than the other domains and the only one i bought separately (godaddy) has 100% reputation when all the other ones tank, right now all my mailboxes got cooked again yet the main domain mailboxes are all at 100%.

My next steps is adding another email verification step and warming for 3 weeks instead of 2 and see how it goes, would appreciate some advice and insights as this is starting to make me go bald.