HubSpot Email Deliverability: Why Your Emails Land in Spam (And the Two-Track Fix Most Guides Miss)

According to Email Report Deliverability Benchmark Reports, HubSpot's Marketing Hub averaged 77.7% inbox placement, ranking 12th out of 16 platforms tested. It means roughly one in four emails may not reach the inbox.

For B2B teams running HubSpot, this number tracks with what the symptoms actually look like. Open rates drop. Replies stall. Sequences that used to land start landing in spam, especially in Outlook. Authentication checks pass, content looks clean, and placement still keeps declining.

The reason most teams stay stuck is simpler than it looks. HubSpot is treated as one platform, but it sends emails through two completely different systems, each with its own infrastructure, reputation signals, and failure points. Marketing Hub uses HubSpot's shared SMTP. Sales Hub Sequences send through your connected Gmail or Microsoft 365 inbox. 

In this blog, we break down both the paths, show how to identify which one is causing the problem, and walk through the fixes specific to each.

Hubspot Sending Paths

The two different Hubspot sending paths influence how your messages are processed, authenticated, and ultimately placed in the inbox. Understanding these paths is critical to diagnosing inconsistencies and making sense of why performance can vary, even when everything looks correctly set up on the surface.

Path 1: Marketing Hub emails (including workflow emails and transactional emails):

Marketing Hub sends through HubSpot's own SMTP infrastructure, on shared IPs by default. Authentication (SPF, DKIM, DMARC) is configured against HubSpot's sending domain, so deliverability rests on two layers:

1. HubSpot's IP reputation 
2. Your own domain setup

Path 2: Sales Hub Sequence emails (including one-to-one emails from contact records and Conversations inbox):

Sales Hub sends through your connected Gmail, Microsoft 365, or IMAP inbox, with HubSpot acting as the automation layer rather than the sender. However, authentication, IP reputation, and sending limits all come from Google or Microsoft, not HubSpot's infrastructure

Here’s a difference between both Marketing Hub path and Sales Hub path 

Understanding which path you're on is step one. Everything else follows from there.

Why Marketing Hub Emails Go to Spam (And What Actually Fixes It)

When Marketing Hub emails land in spam, the issue is almost always one of the following three things: 

1. Broken authentication
2. Poor list quality, or 
3. Content that triggers spam filters. 

These map directly to the three pillars of HubSpot email deliverability:

1. Sender reputation (built on engagement)
2. Email content, and 
3. Sending setup.

Fix authentication: 

The most common and fixable Marketing Hub spam issue is incomplete domain authentication. If recipients see your emails arriving from "[your name] via hubspotemail.net" instead of your actual domain, your SPF or DKIM records are either missing or misconfigured. 

This is one of the leading reasons Marketing Hub emails end up in spam, and inbox providers have grown noticeably less lenient about authentication gaps in recent years.

Three protocols need to be in place and aligned to avoid this issue:

•  SPF (Sender Policy Framework) confirms which servers are allowed to send for your domain. Maintain a single SPF record that includes HubSpot (include:<portal-id>.spf01.hubspotemail.net). Multiple SPF records break validation.     
•  DKIM (DomainKeys Identified Mail) adds a cryptographic signature so providers can verify the email wasn't altered in transit. HubSpot provides two CNAME records (hs1, hs2), both of which must resolve correctly.
• DMARC (Domain-based Message Authentication, Reporting & Conformance) ties SPF and DKIM together and tells providers what to do when authentication fails. Start with p=none to monitor, then move to quarantine and reject once traffic stabilizes.

According to The Digital Bloom's 2025 B2B deliverability report, only 18.2% of the top 10 million domains have valid DMARC records, and fully authenticated senders are 2.7x more likely to reach the inbox. 

For step-by-step setup, see MailReach's guide on implementing SPF, DKIM, and DMARC. You can also verify your current setup with the MailReach free SPF checker and free DKIM checker.

Clean your lists before blaming HubSpot

Sender reputation is driven by engagement signals, like opens, replies, and low spam complaint rates. When you blast emails to stale CRM lists full of unengaged contacts, bounced addresses, or generic emails like contact@company.com, inbox providers see low engagement and flag your domain as risky.

HubSpot has a built-in graymail suppression feature that automatically excludes unengaged contacts from marketing sends. Many users either don't know about it or disable it because it reduces their apparent send volume. Sending to 10,000 contacts who ignore you damages reputation more than sending to 2,000 who engage.

Google's bulk sender requirements (enforced since February 2024) mandate keeping spam complaint rates below 0.1%, with 0.3% triggering filtering or outright rejection. Every unengaged contact on your list is a potential complaint waiting to happen.

Test where your emails actually land

HubSpot's email analytics show whether an email was "delivered," but "delivered" in Hubspot means the recipient's server accepted it. It doesn’t verify whether the email reached the inbox or not. Your email could be sitting in the spam folder or the promotions tab, and HubSpot's dashboard won't tell you.

According to a 2025 Sinch Mailgun report, only 13% of outreach teams actually test inbox placement. The other 87% are just guessing and sending without inbox placement testing.

MailReach's email spam test works differently from surface-level spam score checkers. You send your email under real sending conditions to a list of 30+ real inboxes across Gmail, Outlook, Yahoo, and other providers. The test shows exactly where your email landed, inbox, promotions, or spam, broken down by provider. 

Why Sales Hub Sequence Emails Go to Spam (And How Warmup Fixes It)

Sales Hub Sequence emails are not sent through Hubspot but they are sent through your connected Gmail or Microsoft 365 inbox, using Google's or Microsoft's infrastructure.

For B2B cold outreach, this is the cleaner setup. You're sending from a legitimate business inbox on a trusted provider, not a third-party ESP's shared IP pool. It only works if the connected inbox already has sender reputation, which most HubSpot sales teams haven't built before they start enrolling contacts

HubSpot Sequences sending limits by plan

HubSpot enforces daily sending limits on connected inboxes to prevent abuse:

These limits exist because Google and Microsoft will throttle or block accounts that send too many automated emails too fast, which brings us to the next problem.

Why Microsoft blocks HubSpot Sequences (and how to prevent it)

If your HubSpot sequences are underperforming with Microsoft inboxes, remember that Outlook and other Microsoft mailboxes apply a stricter, often less transparent filtering logic that can flag even well-configured outreach. 

In fact, a lot of Hubspot users repeatedly complain about how Microsoft frequently warns of seeing anomalous behavior in the mailbox and then shortly after,  blocks the mailbox, leaving the remainder of sequence emails unsent

To make sense of what’s happening, and how to stay ahead of it, you need to understand the underlying triggers that influence how these sequences are evaluated. 

It happens because Microsoft's algorithms detect sudden pattern changes. For example, a mailbox that normally sends 5–10 personal emails per day suddenly fires off 50 templated messages in rapid succession. Without prior sending history and engagement signals, Microsoft treats it as potential spam or compromise.

However, the fix isn't to reduce Sequences volume to zero, but to build sender reputation on the connected inbox before launching campaigns.

How to warm up your connected inbox for HubSpot Sequences

HubSpot has no built-in email warmup tool so if you're running Sequences through a new or underused Gmail or Microsoft 365 inbox, you need an external warmup solution.

MailReach's email warmup connects directly to your Gmail or Microsoft 365 inbox, the same inbox your Sequences send from. It generates positive interactions (opens, replies, stars, spam folder removal) from a network of over 30,000+ real Google Workspace and Microsoft 365 business inboxes. This builds trust with the exact providers that decide where your Sequence emails land.

Here's what the warmup process looks like:

• Week 1–2: MailReach gradually ramps sending volume on the connected inbox. Warmup emails receive authentic engagement from real business inboxes. No mass campaigns are sent during this phase.
• Week 3+: Once sender reputation stabilizes (visible through MailReach's reputation score), begin Sequences at low volume and increase gradually.
• Ongoing: Continue warmup alongside campaigns to maintain sender reputation. Stopping warmup while actively sending cold outreach often causes reputation to decline.

For a deeper dive on the mechanics, read how email warmup works.

The Email Health blind spot HubSpot doesn't tell you about

HubSpot's Email Health dashboard is a useful monitoring tool, but only for Marketing Hub emails. If you're running cold outreach through Sequences, HubSpot gives you zero visibility into your connected inbox's sender reputation. You don't know if your emails are landing in spam until a prospect tells you, or worse, until your pipeline dries up.

MailReach's reputation score fills this gap by measuring how Google and Microsoft perceive your connected inbox based on engagement signals, bounce patterns, and spam complaints. You can track it per domain, per inbox, and per provider.

Why a dedicated IP is wrong for most HubSpot accounts

The "get a dedicated IP to fix spam" instinct is one of the most expensive mistakes HubSpot Marketing Hub users make. If the problem is tied to email behavior (frequency, relevance, poor opt-in management, purchased lists), a dedicated IP will not improve anything but will likely make things worse because you can no longer benefit from other senders' positive reputation on the shared pool.

HubSpot recommends dedicated IPs only for accounts sending over 100,000 emails per month, and the automated warmup takes 40 days. For the vast majority of B2B teams using Marketing Hub, the shared IP is actually fine because most often the real problems are authentication, list quality, and sender reputation on connected inboxes.

Dedicated IPs are tied to Marketing Hub’s email infrastructure, not Sales Hub Sequences sent through connected Microsoft 365 or Google Workspace mailboxes. With Sales Hub, deliverability depends primarily on the reputation and configuration of the connected mailbox itself.

When you strip away platform blame, the actual causes of HubSpot email deliverability problems are almost always user-side:

• Broken or incomplete SPF/DKIM/DMARC setup
• Purchased or scraped contact lists with high bounce rates
• Sending to unengaged contacts without graymail suppression
• Running cold outreach through Marketing Hub (an opt-in ESP) instead of through Sequences (connected inbox)
• Not warming up connected inboxes before launching Sequences
• No inbox placement testing, relying on "delivered" as a proxy for "inboxed"

Fix HubSpot Email Deliverability: Step-by-Step Action Plan

Regardless of which sending path you're on, start with these steps and branch based on your use case.

Step 1: Identify your sending path:

Are you sending through Marketing Hub (newsletters, workflows, transactional emails) or through Sales Hub Sequences (cold outreach, follow-ups via connected inbox)? Many teams use both, in which case, run both tracks.

Step 2: Authenticate your domain:

This applies to both paths. Set up SPF, DKIM, and DMARC. Verify link branding so tracked links use your domain, not HubSpot's default.

Step 3 (Marketing Hub) Clean lists and test placement:

Enable graymail suppression. Remove hard bounces and unengaged contacts. Run an inbox placement test before every campaign to see where emails actually land across providers.

Step 4 (Sales Hub Sequences): Warm up connected inboxes:

Before launching any Sequence, warm up your Gmail or Microsoft 365 inbox for at least 14 days using MailReach. Start Sequences at low volume and scale gradually. Continue warmup alongside campaigns to maintain deliverability.

Step 5: Test before every campaign or sequence:

Make inbox placement testing a standard pre-send step, not a one-time audit. Gmail and Outlook filters update regularly, what worked last month may not work today.

Step 6: Monitor ongoing:

For Marketing Hub, use HubSpot's Email Health dashboard. For Sequences, use MailReach's reputation score. It's the only way to track sender reputation on connected inboxes since HubSpot doesn't provide it.

How MailReach Fills the Gaps HubSpot Leaves Open

HubSpot is a strong CRM and marketing platform but it was not built as a deliverability tool, and it leaves three specific gaps:

Gap 1: No email warmup:

HubSpot has no native feature to warm up connected inboxes before running Sequences. MailReach's warmup network of 30,000+ real Google Workspace and Microsoft 365 inboxes builds sender reputation through authentic engagement, including opens, replies, stars, and spam removal. 

Gap 2: No inbox placement testing:

HubSpot shows "delivered" but not where emails actually land. MailReach's spam test sends to 30+ real inboxes under real conditions and shows inbox vs. spam vs. promotions placement, broken down by provider. Free tests available daily.

Gap 3: No sender reputation visibility for Sequences:

HubSpot's Email Health only covers Marketing Hub. MailReach's reputation score tracks the health of your connected inbox per domain and per provider, with Slack alerts when scores drop.

Agencies managing multiple client HubSpot accounts can use MailReach's per-domain reputation tracking, tag-based organization, and API for scale. See the MailReach agency page for details.

The Real Question Isn't "Is HubSpot Email Deliverability Bad?"

The real question should be which HubSpot email product are you using, and is your setup right for it? If you're sending marketing emails through Marketing Hub, your fix is authentication, list hygiene, and inbox placement testing to see where emails actually land. HubSpot's shared IP infrastructure handles the rest.

If you're running outreach through Sales Hub Sequences, your fix is warming up your connected inbox so Google and Microsoft trust your domain before you start sending campaigns. HubSpot gives you zero visibility into this, but MailReach does.

Most deliverability problems aren't platform problems. They're setup and reputation problems. Diagnose honestly, fix what's actually broken, and test before you send.

Not sure if your HubSpot emails are reaching the inbox? Run a free spam test, no sign-up required.