Deliverability Test — Inbox Type Comparison
Compare reply rates, bounce rates, and positive reply rates broken down by inbox type (SMTP, Gmail / G Suite, Outlook / Office365) across your Smartlead account. Use it to answer "are my Gmail inboxes performing better than my SMTP ones?" or "why is one inbox type bouncing more than the others?"
Why this exists
Different inbox types have different deliverability characteristics:
- Gmail / G Suite — highest trust, fewest bounces, often best reply rates
- Office365 — good reputation, but stricter spam filtering
- SMTP (Zapmail, Maildoso, Mailforge, custom) — varies wildly by provider, often has higher bounces in the first 30 days of domain life
If your campaigns mix inbox types, this skill shows which type is earning its keep.
What you need
SMARTLEAD_API_KEY in env- Optional:
--client-id=<id> for sub-clients
- Optional:
--days=<N> lookback (default 7)
Steps
# Full account, last 7 days
npx tsx scripts/inbox-type-compare.ts
# Specific sub-client, 14-day lookback
npx tsx scripts/inbox-type-compare.ts --client-id=5560 --days=14
# Just show today
npx tsx scripts/inbox-type-compare.ts --days=1
Output
Inbox Type Comparison — last 7 days
Type Inboxes Sent Replies Bounces Reply % Bounce %
--------------- ------ ------- ------- ------- ------- --------
G Suite 12 3,120 42 12 1.35% 0.38%
Office365 24 6,440 65 28 1.01% 0.43%
SMTP 44 10,780 55 98 0.51% 0.91%
--------------- ------ ------- ------- ------- ------- --------
TOTAL 80 20,340 162 138 0.80% 0.68%
Takeaways:
- G Suite has the highest reply rate (1.35%) and lowest bounce rate.
- SMTP reply rate is 60% lower than G Suite — investigate domain reputation.
- SMTP bounce rate is 2x average — run /email-deliverability-audit on SMTP domains.
How it works
- Pulls all email accounts via
/email-accounts API paginated
- Groups by
type field (GMAIL, OUTLOOK, SMTP, etc.)
- For each campaign that uses these inboxes, pulls per-inbox stats from
/campaigns/{id}/analytics and /campaigns/{id}/sequence-analytics-by-email-account
- Aggregates sent/replies/bounces within each type group
- Prints formatted table
Common gotchas
- Reply rate here is RAW, not positive. For positive reply rate (the more important metric), use
/positive-reply-scoring.
- Small inbox counts are noisy. If you only have 2 Gmail inboxes and 40 SMTP ones, the Gmail numbers aren't statistically meaningful.
- Inbox type labels can be surprising. Some providers register as "SMTP" even when they're technically Gmail-proxied. Trust the label Smartlead gave them.
What to do next
If one inbox type is underperforming: /smartlead-inbox-manager to retire the bad ones (tag retired, disable warmup). If replacements are needed, /zapmail-domain-setup-public to provision new domains on a different provider type.
If all types are healthy: back to the weekly rhythm via /cold-email-weekly-rhythm.
Or wait: small sample sizes (<500 sends per type) are noisy. If your results are inconclusive, run again in 7 days with more data.
Related skills
/email-deliverability-audit — full audit (SPF/DKIM/DMARC + reputation + spam placement)/positive-reply-scoring — the metric that matters, not just reply rate/smartlead-inbox-manager — rotate out bad inboxes, tag by performance
Scripts
scripts/inbox-type-compare.ts — pulls + compares per-type rates