Email deliverability FAQ
Email deliverability,
answered clearly
Email deliverability is your ability to reach the inbox instead of the spam folder. Below: what the core terms mean, the 2024–2025 sender rules from Google, Yahoo and Microsoft, when you actually need help — and how MailSoar works. Straight, sourced answers.
01 · Working with MailSoar
Who we are, who we work with, and the results to expect.
The practical questions teams ask before they engage us.
MailSoar is an email deliverability agency. We are a senior team of around 25 consultants who diagnose, fix, monitor, and scale email programs so that messages reach inboxes rather than spam folders. We work across every major ESP, within the stack you already use, and cover the whole journey: “Find” diagnoses the root cause, “Fix” implements the recovery, and “Grow” scales volumes and re-engages audiences while maintaining deliverability, and “Run” maintains compliance and deliverability. Most engagements start with the audit: it gives you a clear read on the real root causes, so every fix that follows targets what actually moves inbox placement.
We’re a strategic partner, not a tool or an individual freelancer.
Results depend on the starting point, but clients routinely move from spam-folder problems to reliable inbox placement, with some moving from about 60% to 98% inbox placement. Most Fix projects run 2–6 weeks and deliver measurable improvement in placement and engagement — the outcomes that actually drive revenue.
MailSoar works with startups through enterprises across SaaS, ecommerce, finance, events, B2B and service businesses — anywhere email drives revenue. Whether you send transactional, marketing or lifecycle email, the work adapts to your volume and infrastructure, from a single sending domain to complex multi-domain, multi-ESP setups.
→ Speak with a deliverability expert
Almost certainly. We work inside your existing stack rather than moving you to a new one, so there’s no obligation to move somewhere else or dump your existing stack. MailSoar’s consultants are native to the platforms our clients already send from, across the whole sending chain:
Marketing & engagement platforms — Klaviyo, Braze, Iterable, Customer.io, HubSpot, Mailchimp, Brevo
Enterprise suites — Salesforce Marketing Cloud
Transactional infrastructure — SendGrid, Amazon SES, Mailjet
If you send from something less common, tell us which, and we’ll say plainly if we’re not the right fit.
We cover the full lifecycle of an email program: diagnose, repair, maintain, scale.
• Find — a root-cause audit of your infrastructure, authentication, and sender reputation. Around eight days of analysis, delivered as a 30–40 page report and a one-hour call, ending in a recovery plan you approve.
• Fix — implementation of that plan inside your existing stack, typically over two to six weeks.
• Grow — scales volumes and re-engages audiences while maintaining deliverability.
• Run — keeps your deliverability at its best with deliverability monitoring and blacklist & spam alerting, so your results keep improving.
Most clients start with Find: a precise diagnosis means every fix targets the real cause, so you reach the inbox faster. Many move to Grow to turn reliable deliverability into additional revenue, then stay on Run to keep placement rock-solid.
Yes — a large portion, around 80%, of MailSoar’s clients are US companies, and we have teammates in the United States. US senders are our core market, so we work with Gmail, Yahoo, and Microsoft on bulk sender requirements every day. You get consultants in your own time zone, working remotely inside the tools you already use.
Our consultants work in English, French, and Spanish. That means international teams get support in their own language — useful when deliverability work involves marketing, IT, and legal stakeholders who aren’t all comfortable in English.
Yes. MailSoar has a strong European footprint, with consultants based in Europe, including the United Kingdom and France, serving European clients across many sectors.
Our consultants are distributed across the United States, Asia, and Europe, so you get senior deliverability expertise in your own time zone and language, wherever your team sits.
Yes. We support clients running email programs across multiple jurisdictions, and our consultants know the frameworks that shape sending practice — GDPR in Europe, CAN-SPAM in the US, CASL in Canada, and CCPA/CPRA in California.
In practice, that governs how you collect consent, build lists, handle unsubscribes, and retain data, all of which feed straight back into deliverability. We advise on sending practice, not on the law: your counsel owns the legal sign-off, we make sure the way you send holds up in every market you send to.
02 · Emails not reaching the inbox
It’s usually a matter of sending behavior, audience management, or a lack of correct technical details — and each leaves a different fingerprint. Reputation damage builds gradually and shows up at your largest providers first. Authentication failures tend to be all-or-nothing and visible in your DMARC reports. A blocklisting produces hard bounces that name their source. Engagement decay usually appears at Gmail before anywhere else. The trap is guessing which one — fixing the wrong cause wastes weeks. That’s why the work starts with Find, a root-cause audit of your infrastructure, authentication, and sender reputation. Once the real driver is identified and the plan approved, Fix implements the remediation inside the stack you already use.
→ Start with a deliverability audit
A sudden drop points to a specific trigger, not a slow decline — and the timing is usually your best clue. Look at what changed in the days before it started: a list import, a campaign to a cold segment, a DNS or ESP change, or a new sending domain. A reputation hit, a fresh blocklisting, and a spike in complaints all look identical from where you sit, but each calls for a different response. We walk through those triggers in order, with what to check for each one.
→ Read the full breakdown
You can check public blocklists yourself — but the ones that actually affect inbox placement aren’t always public, which is where most senders get it wrong. Spamhaus, SURBL, and Barracuda take minutes to query. The internal reputation systems at Gmail, Microsoft, and Yahoo can’t be queried at all, and they carry far more weight. A clean public record, with mail still landing in spam, almost always means the problem lies somewhere you can’t look up. Our walkthrough covers what a listing actually does to your inbox placement, how to confirm you’re on one, and the steps to get removed.
→ What it means, and how to get delisted
A falling open rate is often a deliverability problem in disguise, but Apple Mail Privacy Protection also distorts the metric, so it needs careful reading. Before concluding anything, split the trend by mailbox provider. A decline concentrated in Gmail or Outlook suggests inbox placement. A uniform decline across every provider usually points to content or list fatigue instead. Read as a single average, the two are indistinguishable — which is how most teams end up rewriting subject lines to solve a reputation problem.
→ How to read the drop properly and fix it
Yes. Reputation doesn’t transfer between platforms, so a new ESP means a cold start that needs proper warm-up and authentication. The pattern is nearly always the same: authentication records get re-pointed but never fully re-validated, and mail is sent at pre-migration volume on IPs with no history behind them. Providers read that as a brand-new sender behaving like an established one, and filter accordingly. Recovery is usually faster than the first warm-up, since your list and content are already proven — the path depends mostly on how long ago you moved.
A migration is one of the few moments when deliverability is easy to break and slow to repair, and the damage is rarely visible until weeks of sending have already taught the providers the wrong thing. It’s the point in an email program where bringing in a consultant pays for itself — ideally before the switch, not after the drop.
03 · Google, Yahoo & Microsoft rules
The 2024–2025 requirements now decide whether bulk mail reaches the inbox at all.
Since February 2024, senders emailing Gmail and Yahoo in bulk (5,000+ messages a day) must meet four requirements: authenticate with SPF, DKIM and DMARC; send from a domain with valid DNS records; offer one-click unsubscribe (List-Unsubscribe); and keep the Gmail spam-complaint rate below 0.3%. Mail that doesn’t comply is throttled, filtered to spam, or rejected outright.
In May 2025, Microsoft began enforcing similar rules for high-volume senders to its consumer domains (Outlook.com, Hotmail, Live). Senders of 5,000+ messages a day must pass SPF, DKIM and DMARC or see their mail routed to the Junk folder, with outright rejection phased in over time. It aligns Microsoft with the Google/Yahoo 2024 standard: authentication is now table stakes across every major mailbox provider.
The 5,000-a-day threshold defines the “bulk senders” who face strict enforcement, but the underlying best practices apply to everyone. Gmail and Yahoo recommend SPF, DKIM and DMARC for all senders, and a low-volume sender with a high complaint rate still gets filtered. Properly authenticating and keeping complaints low protects your deliverability at any volume, and future-proofs you as thresholds tighten.
04 · Scaling & volume
Faster than a full warm-up if your reputation is healthy, but volume jumps still need to track engagement, not just a calendar. The real constraint isn’t a fixed daily ceiling — it’s the ratio providers observe between the volume you add and the engagement it produces. Doubling into a highly engaged segment is often safe; the same increase aimed at a re-activated one is not. That’s why a ramp schedule copied from a blog post tends to fail: it knows the dates, not your list. Grow builds that ramp from your own engagement data and watches placement at every step up, so an increase gets slowed down before providers react rather than after.
→ Pace it against your own data
Almost always. Scaling on top of a deliverability problem just multiplies the volume of spam, accelerating reputation damage. There’s one narrow exception: if placement is already healthy and your only limit is infrastructure capacity, you can scale while you optimize.
The real question is which situation you’re in, and that’s a diagnosis, not a guess. That’s what Find settles, with a root-cause read of whether real filtering is in play. If it is, Fix clears it first; if your placement is already sound, you’re ready to scale — which is exactly where Grow comes in, ramping volume safely on the reputation you’ve built, without undoing the work.
→ See how our Grow solution works
It depends on how inactive they are: a short, well-targeted re-engagement window first, then suppress those who don’t respond. Getting this wrong is costly in both directions — suppress too aggressively and you discard subscribers who were still recoverable; re-engage too broadly and you send volume to addresses that may have decayed into recycled spam traps, damaging the very reputation you’re trying to protect. The dividing line comes down to two things: how long it’s been since the last open or click, and how the address was acquired in the first place. It also shifts over time — a threshold that protected you last quarter can become too loose after a growth push. That’s the case for Run: continuous monitoring of placement and engagement means suppression rules get adjusted based on evidence rather than being set once and forgotten.
→ Keep placement stable with Run
05 · Do I need help, and from whom?
Tool, freelancer, in-house, or agency, and when it’s worth bringing in a specialist.
Yes — a lot of it is learnable. Authentication, list hygiene and engagement are all things a capable in-house team can handle, given the time. You need outside help when the root cause isn’t obvious, when email drives enough revenue that a wrong guess gets expensive, or when your setup spans several domains and ESPs where one change ripples into another. If you can’t tell which of those applies to you, that uncertainty is itself the answer — a diagnostic audit settles it in days, not months of trial and error. It comes down to who takes responsibility for fixing the issue, and how quickly you need it resolved.
A tool tells you what’s wrong; a freelancer, an in-house hire, or an agency is what actually fixes it. The real difference is depth and coverage. Deliverability tools surface symptoms — placement, blocklists, reputation — and stop there. A freelancer adds a pair of hands but rarely the full range of expertise. An in-house specialist gives you control, but seniority is hard to hire and easy to lose. An agency like MailSoar brings a senior team, the tooling, and hands-on implementation inside your existing stack — so you’re buying the outcome, not just the diagnosis.
As soon as you encounter a deliverability issue and want full confidence it will be resolved in a timely manner. The moment inbox placement drops without an obvious reason, or right before a change you can’t afford to get wrong, is when to act. The common triggers repeat across clients: Gmail or Outlook starts throttling or blocking you, you’re about to scale volume or migrate ESP, or email has quietly become a channel the business depends on. At that point, recovering even a few points of inbox placement usually covers the engagement several times over.
Pick senior consultants who’ve handled your ESP and your industry, and who lead with diagnosis rather than a fixed playbook. Before you sign, get three things straight: who exactly does the work and how senior they are; whether they’ll run inside your current stack without forcing a migration; and what they’ll report on, and how often. Then ask for case studies with measurable placement improvements — an agency that can’t show placement numbers is showing you activity, not outcomes.
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