Email Deliverability: The Technical Setup Most Firms Miss

Why Your Cold Emails Land in Spam

You wrote the perfect cold email. You targeted the right people. Your message was personalised, concise, and offered genuine value. You hit send. And nothing happened. No opens. No replies. No meetings. Just silence.

The problem is not your messaging. The problem is that your emails never reached the inbox. They landed in spam, the promotions tab, or were blocked entirely by the receiving server. Your prospects never saw them.

Email deliverability is the invisible foundation of every successful outbound sales campaign. It is the technical infrastructure that determines whether your messages arrive in the primary inbox or disappear into the void. Get it wrong and nothing else matters — not your targeting, not your copy, not your offer. Everything depends on deliverability.

This guide covers every technical aspect of email deliverability that B2B service firms need to understand and implement before sending a single prospecting email.

Understanding Email Deliverability: The Basics

Email deliverability is not the same as email delivery. Delivery means the email was accepted by the receiving server (it did not bounce). Deliverability means the email landed in the primary inbox where the recipient will actually see it.

An email can be successfully delivered but still land in:

• Spam folder: The receiving server flagged it as potentially unwanted
• Promotions tab: Gmail determined it looks like marketing content
• Junk folder: Outlook's version of the spam filter
• Quarantine: Enterprise email systems that hold suspicious emails for admin review

Your goal is not just delivery — it is primary inbox placement. And achieving that requires getting the technical foundation right.

The Complete Technical Checklist

1. SPF (Sender Policy Framework)

SPF tells receiving mail servers which servers are authorised to send email on behalf of your domain. Without it, anyone could send emails pretending to be from your domain, and receiving servers have no way to verify legitimacy.

How to set it up:

• Add a TXT record to your DNS settings
• Include all services that send email from your domain (Google Workspace, Microsoft 365, your sending tool)
• Example record: v=spf1 include:_spf.google.com include:amazonses.com ~all
• The ~all at the end means "soft fail emails from unlisted servers" — this is the recommended starting point
• Important: You can only have one SPF record per domain. If you need multiple includes, combine them into a single record.

Common mistakes:

• Forgetting to include your sending tool in the SPF record
• Having multiple SPF records (which invalidates all of them)
• Using +all instead of ~all or -all (which authorises everyone to send as your domain)

2. DKIM (DomainKeys Identified Mail)

DKIM adds a digital signature to your emails that proves they were not tampered with in transit. It is like a wax seal on a letter — the receiving server can verify that the email arrived exactly as it was sent.

How to set it up:

• Generate a DKIM key pair in your email provider (Google Workspace, Microsoft 365, or your sending platform)
• Add the public key as a TXT or CNAME record in your DNS
• Verify the signature is being applied by sending a test email and checking the headers
• Most email providers have step-by-step guides for DKIM configuration

Why DKIM matters for cold email:

• Without DKIM, your emails look suspicious to receiving servers
• DKIM failures can cause emails to be flagged as spam even if your content is perfectly clean
• All major email providers (Gmail, Outlook, Yahoo) check DKIM as part of their spam filtering

3. DMARC (Domain-based Message Authentication, Reporting and Conformance)

DMARC ties SPF and DKIM together and tells receiving servers what to do if authentication fails. It also provides reporting so you can monitor who is sending email using your domain.

How to set it up (phased approach):

Phase 1 — Monitoring (Weeks 1-4):

v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com

This tells servers to report authentication failures but take no action. Use this period to identify all legitimate email sources and ensure they pass SPF and DKIM.

Phase 2 — Quarantine (Weeks 5-8):

v=DMARC1; p=quarantine; rua=mailto:dmarc@yourdomain.com

Failed emails are sent to spam rather than delivered to the inbox. This protects your domain while allowing you to catch any remaining configuration issues.

Phase 3 — Reject (Week 9+):

v=DMARC1; p=reject; rua=mailto:dmarc@yourdomain.com

Failed emails are rejected outright. This is the strongest protection and signals to receiving servers that your domain is well-managed.

4. Secondary Domains: Protecting Your Primary Brand

Never send cold outreach from your primary business domain. This is the single most important rule of email deliverability for outbound sales. Here is why:

• Cold email inherently carries some spam risk — even the best campaigns trigger occasional spam reports
• If your primary domain reputation gets damaged, it affects ALL your business email: client communications, invoices, proposals, and internal messages
• Recovery from a damaged domain reputation can take months
• Secondary domains isolate the risk, protecting your core business communications

Best practices for secondary domains:

• Buy 2-3 similar domains that are clearly related to your brand (e.g., if you are maven.com, buy getmaven.co, trymaven.io, or mavengroup.co.uk)
• Set up professional email hosting on each domain (Google Workspace or Microsoft 365 — avoid cheap hosting providers as they share IP addresses with spammers)
• Configure SPF, DKIM, and DMARC on every secondary domain exactly as described above
• Create a simple website on each secondary domain (even a single landing page) — domains with no web presence look suspicious
• Warm up for 2-3 weeks before sending any cold outreach

5. Domain Warm-Up: Building Sender Reputation From Zero

New domains have no sending history, which means email providers have no basis for trusting them. You need to build a positive reputation gradually before sending cold outreach at volume.

The warm-up process:

• Week 1: Send 5-10 emails per day to engaged contacts (people who will open and reply). These can be colleagues, friends, or warm contacts who agree to participate in the warm-up.
• Week 2: Increase to 15-25 per day. Mix engaged contacts with warm prospects who are likely to open.
• Week 3: Increase to 30-50 per day. Begin introducing cold prospects gradually.
• Week 4+: Maintain 40-50 per day per account. This is your sustainable sending volume for cold outreach.

Automated warm-up tools:

Tools like Instantly, Warmbox, and Lemwarm automate the warm-up process by exchanging realistic emails between accounts in their network. These conversations generate opens, replies, and positive engagement signals that build your sender reputation.

Important: Warm-up should continue indefinitely, even after you begin cold outreach. Most tools run warm-up conversations in the background alongside your actual campaigns.

6. Sending Limits and Throttling

Even with fully warmed domains, there are limits to how much you should send:

• Maximum 50 emails per day per account for cold outreach
• Spread sending throughout the day — do not send 50 emails in a single burst at 9 AM
• Use multiple accounts across multiple domains to increase total volume while keeping per-account volume low
• Typical setup for a small firm: 3 domains x 3 accounts per domain x 40 emails per day = 360 cold emails per day total capacity

7. List Hygiene and Email Verification

Sending to invalid email addresses is one of the fastest ways to damage your sender reputation. Every bounced email is a negative signal to receiving servers.

Best practices:

• Verify every email before sending using services like NeverBounce, ZeroBounce, or Apollo.io's built-in verification
• Remove catch-all domains from your lists (these domains accept all emails, making it impossible to verify individual addresses)
• Clean your lists regularly — email addresses go stale as people change jobs, companies rebrand, and domains expire
• Target a bounce rate under 3% — above this threshold, your sender reputation degrades rapidly

Content Best Practices for Deliverability

Beyond technical setup, the content of your emails affects deliverability:

Avoid Spam Trigger Words

Words and phrases like "free," "guarantee," "act now," "limited time," "click here," and "buy now" trigger spam filters. Write your cold email copy as you would write to a colleague — natural, conversational, and free of marketing language.

Use Plain Text Formatting

HTML-heavy emails with images, buttons, colours, and fancy layouts signal "marketing email" to spam filters. Plain text emails look personal and land in the primary inbox more reliably. For cold outreach, plain text is always the right choice.

Keep Links Minimal

One link per email is ideal. Multiple links trigger spam filters. Avoid link shorteners (like bit.ly) entirely — they are heavily associated with spam and phishing.

Include an Unsubscribe Mechanism

Required by law (GDPR in the UK, CAN-SPAM in the US) and expected by email providers. A simple line at the bottom: "If you would rather not hear from us, just reply and let us know" satisfies the requirement without a formal unsubscribe link that looks like marketing email.

Maintain a Healthy Text-to-Link Ratio

If your email is 50 words with 3 links, spam filters will flag it. Keep your emails 60-100 words with 0-1 links.

Monitoring Your Deliverability Ongoing

Deliverability is not a one-time setup — it requires ongoing monitoring:

Tools to Use

• GlockApps: Test inbox placement across Gmail, Outlook, Yahoo, and corporate email systems. Run a test before every major campaign launch.
• Mail-tester.com: Quick score check for individual emails. Send a test email to their address and get an instant deliverability score.
• Google Postmaster Tools: Monitor your domain reputation specifically with Gmail (the largest email provider globally). Watch for reputation drops and investigate immediately.
• Your sending platform's analytics: Apollo.io, Instantly, and other sending tools provide open rate, bounce rate, and spam complaint data.

Metrics to Watch Weekly

• Inbox placement rate: Target 90%+ (the percentage of emails landing in the primary inbox)
• Bounce rate: Keep under 3% (hard bounces indicate bad email addresses)
• Spam complaint rate: Keep under 0.1% (spam complaints are the most damaging signal)
• Domain reputation: Monitor in Google Postmaster — watch for drops from "High" to "Medium" or "Low"
• Open rate trends: Declining open rates over time can indicate deliverability degradation

Red Flags That Require Immediate Action

• Open rates dropping below 30% on previously well-performing sequences
• Bounce rates exceeding 5% on any campaign
• Google Postmaster showing "Low" domain reputation
• Multiple prospects reporting they found your email in spam
• Sudden drops in reply rates with no change to messaging

Common Deliverability Killers (And How to Avoid Them)

1. Sending too much too fast — The number one mistake. New domains need gradual warm-up. Established domains need consistent, moderate volume. Sudden spikes trigger spam filters.
2. Poor list hygiene — Sending to invalid, outdated, or purchased email lists. Always verify before sending.
3. Spam trigger words and formatting — Marketing language, excessive links, HTML formatting, and images all trigger filters.
4. No authentication (SPF/DKIM/DMARC) — Without these records, your emails look illegitimate to every receiving server.
5. Sending from your primary domain — One spam complaint can damage your business email reputation for months.
6. No unsubscribe mechanism — Both illegal and a deliverability risk.
7. Shared IP addresses — Cheap email hosting shares IP addresses with other senders, including spammers. Use Google Workspace or Microsoft 365.
8. Ignoring deliverability monitoring — Problems compound quickly. A small issue ignored for two weeks can become a major reputation crisis.

The MAVEN Approach to Email Deliverability

When we build outbound sales systems for our clients at MAVEN, deliverability setup is always the first priority. Before a single prospecting email is sent, we ensure:

• All secondary domains are purchased, configured, and hosted on Google Workspace or Microsoft 365
• SPF, DKIM, and DMARC are verified and passing on every sending domain
• Email accounts are created with professional signatures and configured in the sending platform
• Domain warm-up is running and building positive reputation signals
• Sending limits are programmed to protect reputation long-term
• Deliverability monitoring dashboards are set up and reviewed weekly
• List verification processes are established to maintain data quality

This infrastructure phase typically takes 2-3 weeks — and it is the most important 2-3 weeks of the entire engagement. Without it, everything else fails.

Get Your Deliverability Right

If email deliverability sounds technical, that is because it is. But it is not optional. If you want your outbound sales efforts to actually reach inboxes and generate meetings, the technical foundation must be flawless.

Book a virtual coffee and we will audit your current email setup and identify any deliverability issues that are undermining your outreach. You can also explore our Apollo.io partner page for information on the tools we use, check our services for our full engagement overview, or browse our free resources for guides you can implement immediately.

Frequently Asked Questions About Email Deliverability

"How do I know if my emails are landing in spam?"

The most reliable method is using a tool like GlockApps, which sends test emails to seed accounts across major providers and reports exactly where each email lands. You can also ask a few trusted contacts to check their spam folders after you send them a test email. Declining open rates on previously well-performing sequences are a strong indicator of deliverability problems.

"How long does it take to recover from a damaged domain reputation?"

Recovery time depends on the severity of the damage. Minor reputation drops (from "High" to "Medium" in Google Postmaster) can recover in 2-4 weeks if you reduce volume, clean your lists, and focus on engaged recipients. Major damage (landing on blocklists or having "Low" reputation) can take 2-6 months. In severe cases, it may be faster to start with new domains. This is exactly why we recommend never using your primary domain for cold outreach.

"Do we need to warm up every new email account, or just new domains?"

Both. New domains need warm-up to build domain reputation. New email accounts on existing domains also benefit from warm-up, though the process is shorter (1-2 weeks instead of 2-3 weeks) because the domain already has some reputation.

"What is the maximum number of cold emails we should send per day?"

For cold outreach, keep it under 50 emails per day per email account. For a firm wanting to send 200+ emails per day, you need multiple accounts across multiple domains. A typical setup of 3 domains with 3 accounts each gives you 9 sending accounts, or approximately 350-450 emails per day at safe volume levels.

"Should we use a dedicated IP address?"

For most B2B service firms doing moderate cold outreach volume (under 1,000 emails per day), shared IPs through Google Workspace or Microsoft 365 are fine. Dedicated IPs make sense for firms sending 5,000+ emails per day, but they come with the responsibility of managing your own IP reputation — which requires expertise and consistent sending volume.

"How does GDPR affect cold email in the UK?"

Under GDPR, B2B cold email is permitted under the "legitimate interest" legal basis, provided your message is relevant to the recipient's professional role, you identify yourself clearly, you provide an easy way to opt out, and you honour opt-out requests promptly. This is one of the reasons proper targeting and ICP definition is so important — sending relevant messages to appropriate recipients is both a deliverability best practice and a legal requirement.