The part cleaning can’t fix
You paid for a validation tool. You removed the bounces. You followed the best practices. Your tool answered the wrong question.
Yanna-Torry Aspraki
Litmus Coach 2020·Ask a Deliverability Expert·8,000+ lists reviewed
01Worked example
The same SMTP exchange, read twice. The first reading is the one you paid for. The second is the one that explains your spam folder.
> RCPT TO:<sales@redactedclient.example>
< 250 2.1.5 OK
> DATA
< 354 Start mail input
...
< 250 2.0.0 Ok: queued as A1B2C3
# Validator verdict: VALID. No bounce. Done.
Now the same bytes, read with the history behind them.
> RCPT TO:<sales@redactedclient.example>
< 250 2.1.5 OK
# recipient domain is on a major blocklist
# last engagement: 412 days ago
> DATA
< 354 Start mail input
...
< 250 2.0.0 Ok: queued as A1B2C3
# queued to a mailbox dormant past the 12-month window
What we read into the same trace. The recipient domain is on a major blocklist. The mailbox last showed engagement 412 days ago. Yahoo let the underlying account go dormant past the 12-month mark. The 250 OK is a silent accept by a long-inactive address on a listed domain, not a clean delivery. Verdict: Suppress.
Delivered is what left the server. Inboxed is what a person sees.
The validator read the handshake and stopped. We read the history behind it. Same transaction, opposite verdict.
02The autopsy
Your validator ran an SMTP probe against every address on your list.
It opened a connection, issued RCPT TO, and recorded the
response. Addresses that returned a 5xx code, typically
550 5.1.1 User unknown, were flagged as bouncing. You
removed them. Good.
Bounces are not the only thing that hurts deliverability. They are rarely the main thing. The addresses that drag down sender reputation are the ones that do not bounce: long-inactive addresses on domains that changed hands, abandoned inboxes that accept and ignore, role addresses on blocklisted domains that accept and quietly tank your IP.
None of those return a 5xx. Your validator marked them valid. You kept sending. Mailbox providers kept downgrading you.
03The six gaps
Each card names a concrete receiver-side mechanism that accepts your send and degrades your reputation.
A long-inactive address on a domain that changed hands returns
250 OK at the RCPT TO step the same way a
real recipient does. Your validator sees a clean handshake and
labels the address valid. The receiver logs the send against your
sender reputation either way.
An address can be live on a domain currently on a major blocklist. The SMTP transaction still completes. Mailbox providers treat continued sends to listed domains as a strong negative signal even when no bounce is generated.
The February 2024 sender rules gave complaint rate two thresholds, not one. 0.1 percent is the alarm threshold, where inbox providers start flagging you and your domain reputation begins to slip. 0.3 percent is the hard ceiling, where you actively see delivery damage: throttling, spam-foldering, outright blocks. Reading “0.3 percent” as a single line in the sand leaves you thinking you have headroom you don’t. Postmaster Tools surfaces your domain reputation as High, Medium, Low, or Bad, but the reputation drop starts well before you hit the ceiling. Validation tools do not read that signal. Sending to disengaged cohorts pushes complaint rates up without ever bouncing.
A list can be technically deliverable while your sending domain
fails DMARC alignment because the DKIM d= signing
domain does not match the From header organizational domain. The
address is valid. The authentication is not. Validators check the
recipient, not your sending posture.
Mailbox providers score by cohort behavior over rolling windows. A segment that has not opened in 180 days will keep accepting mail at the SMTP layer while quietly routing every send to Promotions or Spam. The address looks fine to a validator. The receiver has already downgraded it.
Yahoo Mail returns 250 OK for many addresses regardless
of whether the mailbox exists, including former accounts that went
dormant past the 12-month window. Validators relying on SMTP probes
cannot distinguish a real Yahoo inbox from a long-inactive address
on the same domain.
04Keep the validator. Add the eyes.
Keep the validator for bounce catching. Layer reputation and trap checks on top.
Review My Emails runs the validation pass and then adds the receiver-side context: domain health, blocklist presence, address pattern risk flags, Postmaster-style engagement scoring, and infrastructure quality on the sending side.
Verdicts come back as Keep, Monitor, or Suppress, each tagged with labels that name the specific risk: long inactive, blocklisted domain, dormant 180 plus days, role address on a listed domain. Not “valid” or “risky”. A named verdict with the reason attached.
05Side by side
Two columns of the same list, two different verdicts. The full head-to-head lives on the comparison page.
Validation tool
Review My Emails
Upload the same list you already cleaned. We will show you what is still on it that should not be. Free credits to start. No credit card.
New questions, deliverability shifts at Gmail and Outlook, and any tool that landed since the last issue. No fluff, no upsell.
You cleaned the list. The spam folder kept you anyway. That’s not a mystery. It’s the gap between delivered and inboxed.
Upload the same list you already cleaned. I’ll read it the second way, and sign what I find.
Yanna-Torry Aspraki
Founder, Review My Emails