Team email deliverability: protect your sender reputation on a shared account

Jean RubensUpdated July 202613 min read

Five teams log into one Brevo account. Each keeps a tidy dashboard and a clear conscience. Yet open rates are drifting down, and more mail is quietly landing in spam. No single campaign explains it, and no single team feels responsible. So what changed?

The shared sender reputation changed. It's the one asset every team draws from and pays into, and it doesn't appear on anyone's dashboard. Protecting it isn't mainly a technical job. It's a coordination job with a technical floor. This guide walks through both: the settings that keep you trusted, and the habits that keep five teams from spending that trust faster than any of them can rebuild it.

What is sender reputation on a shared account?

Sender reputation is the trust score mailbox providers assign to your sending domain and IP, built from how recipients react to your mail. It decides placement, and the margin is thin: in 2026, about 15% of legitimate email never reaches the inbox, with global placement at 84.5% (Validity, \$42 Million a Day, Q2 2026). On a shared account, that score is collective.

A few inputs move that score: how often recipients open and reply, how many mark you as spam, how many addresses bounce, whether your mail is authenticated, and how steady your volume stays. Every team's sends feed all of those signals into the same domain. There's no per-team reputation to hide behind.

That's the mental shift a shared account demands. Your reputation isn't the average of five teams doing fine. It's the running verdict on the domain, and the worst-behaving stream pulls the hardest. Treat it as shared infrastructure, because that's exactly what it is.

Why is a shared account uniquely exposed?

Because reputation is domain-wide and additive, so risk pools where sending does. One sender pushing a spam-complaint rate above 0.30% can degrade inbox placement for every other sender and stream sharing that reputation (Suped, Shared IP pools and sender reputation, retrieved 2026). On a shared account, that "one sender" is often just one team having a rough month.

The teams usually aren't reckless. They're blind. Each meets its own internal rule and still, together, overwhelms shared contacts, because no rule spans every sender at once. We wrote a whole piece on the specific ways this plays out, in the 5 multi-team mistakes that wreck deliverability.

This is why we treat sending governance and deliverability as the same problem seen from two angles. If you want the access-and-frequency control side in depth, our complete guide to Brevo multi-team governance is the companion to this one.

How do SPF, DKIM and DMARC protect a shared domain?

They prove the mail really comes from you, and they're no longer optional. Since February 2024, Google and Yahoo require bulk senders to authenticate with SPF, DKIM and a published DMARC policy, or mail starts skipping the inbox (Google, Email Sender Guidelines, 2024). On a shared account, one properly authenticated domain gives every team a single strong identity instead of several weak ones.

Each record does one job. SPF lists which servers may send for your domain. DKIM signs each message so tampering shows. DMARC tells mailbox providers what to do when a message fails, and lets you see who's sending as you. Configure all three, once, for the shared domain.

The multi-team failure mode is fragmentation. One team plugs in a new tool with its own from-address, another sends from an unaligned subdomain, and suddenly part of your mail fails authentication while the rest passes. Decide the sending-identity strategy centrally, and route every team through authenticated domains.

Which metric decides inbox versus spam?

The spam-complaint rate, more than any other single number. Google downgrades any sender above 0.3%, and that rate is measured across your whole sending domain (Google, 2024). Aim to stay under 0.1% for a working margin. On a shared account, the rate you're judged on is the sum of every team's sends.

Here's the trap. Each Brevo dashboard shows a team its own opens, clicks and unsubscribes. None shows the account's aggregate complaint rate against that 0.3% line. So the single number that can sink everyone is the one number nobody is assigned to watch, until placement drops and the investigation starts.

Give the domain-level complaint rate one owner and a ceiling of 0.1%. When it climbs, that owner traces which send did it and adjusts before mailbox providers react. The multi-team mistakes guide covers the blind-metric problem in more detail.

How does list hygiene protect the shared reputation?

By keeping you off the signals that pull hardest: bounces and spam-trap hits. Email lists decay by roughly 28% a year as people change jobs and abandon addresses (ZeroBounce, Email List Decay, retrieved 2026). On a shared list, nobody owns cleanup, so every team keeps mailing the same aging contacts and feeding the domain the exact signals that lower placement.

Dead addresses don't just fail to convert. They hard-bounce, they hit recycled spam traps, and they produce the long silences that mailbox providers read as disinterest. Each one is a small deduction from a reputation five teams share. Multiply by a database no one prunes and the drift is steady.

Hygiene and access are linked. When a stale "all contacts" export is one click away for any user, cleanup never keeps up. Scoping who can reach which lists, covered in how Brevo permissions let anyone email your whole base, is half the hygiene battle.

Is frequency really a deliverability issue?

Yes, and it's one of the biggest. Over-frequency is the No. 1 reason people leave a list: in 2026, 43% named it as their main reason for unsubscribing (ZeroBounce, Email Statistics Report, 2025). Unsubscribes and complaints are reputation inputs, so additive cross-team frequency is a deliverability problem wearing a marketing hat.

The fix is a limit, not silence. A common working ceiling is 2 to 4 marketing emails per contact per month, tuned to engagement rather than applied as a blanket rule (Braze, What Is Frequency Capping?, 2025).

The shared-account catch is enforcement. A per-contact ceiling only works if someone can see the contact's total intake across every team and automation. Making that running total visible is the single highest-leverage move for protecting the domain, and it's the heart of the governance guide.

Shared IP, dedicated IP, and what about warm-up?

Most Brevo senders sit on a shared IP pool, where your reputation depends partly on your pool neighbors, and your own complaints can hurt theirs too (Suped, retrieved 2026). A dedicated IP isolates you from strangers, but it puts your reputation entirely on your own shoulders.

A dedicated IP isn't a free upgrade. It needs consistent, fairly high volume to stay warm, because mailbox providers distrust IPs that send in erratic bursts. Below that volume, a shared pool with a good provider usually delivers better than a cold dedicated IP would. Most multi-team accounts are better served fixing coordination than buying an IP.

Whichever you use, the domain reputation is what most consistently follows your mail, so the coordination work in this guide matters more than the IP choice for almost every team sharing one account.

How do you protect deliverability on a shared account?

Set the technical floor once, then govern the shared reputation as one asset. The order matters: authenticate and clean first, because you can't out-coordinate a domain that fails DMARC or mails dead addresses. These six moves take a shared account from hope to something closer to a system, and they work on top of Brevo with no migration.

The floor is technical; the rest is coordination that a shared account can't do on its own. Here's what Brevo covers natively and what needs a layer on top.

Brevo plan capabilities change; verify against Brevo's help center before relying on a specific tier.

Frequently asked questions

Jean Rubens

Co-founder, Sendgate

Jean is a co-founder of Sendgate. He writes about multi-team email governance: sender reputation, send-frequency visibility and deliverability across shared sending accounts.