Authenticate your domain first
Inbox placement starts with trust. Before anything else, set up SPF, DKIM, and DMARC on the connector's Technical tab. Unauthenticated mail is the fastest way into the spam folder: the app's own alert warns it "may land in spam or be rejected."
Aim for Fully Authenticated (all three passing). This one step moves the needle more than any copy tweak.
Warm up the mailbox and keep it Healthy
Reputation is built, not bought. Turn on warm-up and watch the Warmup Score gauge climb toward Healthy (80+). A mailbox reading Warming or Issues (under 40) will place poorly until it recovers.
Don't rush volume on a cold mailbox: sending hard before it's warm is what tanks placement in the first place.
Watch Sender Health for bounce and reputation warnings
In a campaign's Analytics → Sender Health, each mailbox is graded. A red "Health issues" flag appears when bounce rate exceeds 5% ("High bounce rate") or the warm-up score drops below 50 ("Low warmup score"). Both wreck placement.
The campaign dashboard mirrors this with status dots: red past 5% bounce or under 50 score, amber past 2% or under 80. Treat any red as a stop-and-fix signal, not a number to ignore.
Clean the list so you don't bounce
Bounces are placement poison, and they come from bad addresses. Turn on Contact cleaning (Settings → Tools) so FirstSales verifies addresses on import and campaigns "skip dead ones, reducing your bounce rate and protecting sender reputation." It checks MX records, mailbox reachability, disposable and role addresses, and fixes typos.
Keeping bounce rate under 5% (ideally under 2%) is one of the biggest levers you control.
Write mail that doesn't trip spam filters
Content matters too. As you write a sequence, FirstSales runs a deliverability lint that flags spam-trigger phrases, emails that are too long, and competing calls-to-action. Heed those warnings.
- Keep emails short and plain: no hype words, no walls of text.
- One clear ask per email.
- Avoid link-heavy or image-heavy mail on cold sends.
Plain, personal, single-ask emails land in the inbox; salesy blasts land in spam.
Spread volume across warmed mailboxes
Finally, don't concentrate sending. Add several mailboxes at modest Daily Limits (default 50) and let campaigns send across the warmed, healthy ones. Auto-adjust dials each mailbox nightly on its sending health, protecting the pool automatically.
A fleet of healthy mailboxes each sending a little beats one mailbox pushed to its ceiling: and it places far better.
Pro tips
Placement = auth + warm-up + clean list
There's no magic setting. Fully authenticate the domain, warm the mailbox to Healthy, and keep bounce under 5% with contact cleaning. Those three do most of the work.
Red Sender Health dots are a stop signal
Bounce over 5% or warm-up under 50 flags 'Health issues' for a reason: keep sending through it and placement falls further. Pause, fix the list or the mailbox, then resume.
Listen to the deliverability lint
The spam-word / too-long / competing-CTA warnings in the sequence editor map directly to what filters penalize. Clearing them is free placement.
Many mailboxes, modest limits
Spread sends across warmed mailboxes at ~50/day rather than maxing one. Concentrated volume looks like spam to providers; distributed volume looks human.
Frequently asked questions
Does FirstSales have a spam/seed placement test?
No dedicated seed-inbox or spam-test tool. Instead, deliverability is surfaced through domain authentication, the warm-up score, Sender Health warnings, the pre-send deliverability lint, and contact cleaning: the levers that actually drive placement.
What's the single biggest factor in inbox placement?
Domain authentication (SPF, DKIM, DMARC). Unauthenticated mail is treated as suspicious and filtered or rejected, so completing all three is the highest-impact step you can take.
What bounce rate is safe?
Keep it under 5% (that's where the app flags 'High bounce rate' health issues) and ideally under 2% (the amber warning threshold). High bounces signal a dirty list and hurt placement fast.
How do I stop bounces before they happen?
Enable Contact cleaning (Settings → Tools). It verifies addresses on import (MX records, mailbox reachability, disposable/role detection, typo correction) so campaigns skip dead addresses instead of bouncing on them.
What warm-up score should I aim for?
Healthy is 80+. Below 50 the mailbox flags 'Low warmup score' and places poorly; under 40 it reads 'Issues'. Warm the mailbox until it's consistently Healthy before sending at volume.
Does the email content affect placement?
Yes. The sequence editor's deliverability lint flags spam-trigger phrases, over-long emails, and competing CTAs. Short, plain, single-ask emails avoid filters; hypey or link-heavy mail invites them.
Should I send everything from one mailbox?
No. Spread volume across several warmed mailboxes at modest daily limits and let campaigns rotate among the healthy ones. Auto-adjust tunes each nightly, which protects overall placement.