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You’ve built a solid prospecting sequence. Your messages are personalized, your targeting is precise, and your offer is clear. Yet your open rates remain stuck below 20%, and responses are few and far between.
Before you start questioning your copywriting, check one thing: Are your emails actually reaching the inbox?
Deliverability is the often-overlooked aspect of automated email marketing. Most teams set up their sequences, hit "send," and hope for the best. In reality, according to data published by specialized providers Mailreach and Lemwarm, about one in five emails never reaches the recipient's inbox. This figure rises significantly when you automate at scale without taking precautions.
In this article, we cover everything you need to do to ensure your outreach emails land in the inbox, get read, and generate responses.
1. SPF, DKIM, DMARC: The Three Technical Pillars of Email Deliverability
Before you even start thinking about the content of your emails, your technical infrastructure must be flawless. These three protocols form the foundation of your sender reputation.
SPF (Sender Policy Framework)
The SPF is a DNS record that lists the servers authorized to send emails on behalf of your domain. When a mail server receives an email from you, it checks this record to verify that the sender is legitimate.
Without SPF properly configured, your emails are considered potentially fraudulent and may be filtered out or rejected outright.
Example of a DNS configuration:v=spf1 include:_spf.google.com include:sendgrid.net ~all
DKIM (DomainKeys Identified Mail)
DKIM adds a cryptographic signature to every email sent from your domain. This digital fingerprint allows the receiving server to verify that the email has not been altered in transit and that it truly comes from you.
This is a critical authentication layer. The spam filters in Gmail, Outlook, and Yahoo place greater trust in DKIM-authenticated emails than in those that are not.
DMARC (Domain-based Message Authentication, Reporting, and Conformance)
DMARC is the policy that coordinates SPF and DKIM. It tells receiving servers what to do if an email fails the checks: ignore it, quarantine it, or reject it.
It also includes a reporting feature that allows you to receive reports on emails sent on your behalf, including attempts to spoof your domain.
Recommended minimum system requirements:v=DMARC1; p=quarantine; rua=mailto:dmarc@votredomaine.com
These three protocols have been mandatory since February 2024 for all senders who send more than 5,000 emails per day to Gmail and Yahoo, in accordance with the new guidelines published by Google and Yahoo in October 2023. Even below this threshold, configuring them remains essential for any serious outreach effort. Neglecting them is one of the most common mistakes in B2B outreach.
2. Sport-specific warm-ups: why they’re non-negotiable
A brand-new domain that starts sending 200 emails a day on its first day will immediately be flagged as suspicious. Email providers analyze a domain’s history: a sender with no history that suddenly starts sending large volumes of emails looks like a spam domain.
The warm-up process involves gradually increasing your email volume over several weeks, starting with small volumes sent to high-reputation addresses, to build a track record as a reliable sender before launching your campaigns at full capacity.
The recommended warm-up routine
- Week 1: 20 to 30 emails per day at most
- Week 2: 50 to 75 emails per day
- Week 3: 100 to 150 emails per day
- Week 4: 200 to 300 emails per day
- Week 5 and beyond: gradual increase based on observed metrics
This schedule applies on a per-domain and per-email-address basis. If you use multiple sending addresses, each one must go through this process individually.
Automated warm-up tools
Tools like Lemwarm (integrated into Lemlist), Mailreach, or Warmbox automate this process. They send and receive emails within a network of verified addresses, generate positive interactions (opens, replies, and emails not marked as spam), and gradually build your domain’s reputation.
These tools do not replace best practices for sending emails, but they significantly speed up the reputation-building phase. If you already use Lemlist as part of your lead generation automation stack, Lemwarm is directly accessible from your dashboard.
3. The recommended domain structure for prospecting
A common mistake is to use your primary domain for automated cold outreach. If your reputation suffers due to excessive volume or poor practices, all of your professional communications will be affected: internal emails, customer communications, and sales follow-ups.
Best practice is to use subdomains specifically for cold outreach. If your main domain is scal-ia.fr, you can use getscalia.fr, scalia-pro.fr, or hello-scalia.fr for your campaigns. These domains should redirect to your main site, and your email signatures should clearly mention your brand to maintain consistency and build trust.
This setup protects you: if a subdomain is penalized, your main domain remains unaffected.
4. Best practices for sending emails to protect your reputation on a daily basis
Technical configuration is necessary but not sufficient. Your day-to-day sending practices are just as important to your deliverability as your infrastructure.
Stick to the daily limits
Even with a well-established domain, there are thresholds beyond which email providers become suspicious.
With Google Workspace: 500 emails per day per address is the maximum recommended volume for cold outreach. The technical limit in Google Workspace is higher, but exceeding this threshold when conducting cold outreach increases the risk of being filtered out.
With a dedicated SMTP service (SendGrid, Brevo, Mailgun): volumes may be higher, but the domain’s reputation remains the primary limiting factor, regardless of the sending infrastructure.
Opt for a simple email format
Cold outreach emails that resemble marketing newsletters (lots of images, little text, elaborate formatting) are more likely to be filtered out than emails that look like personal correspondence. For cold outreach, an email in plain text or with minimal formatting generally achieves better deliverability rates. This is, in fact, a fundamental principle of effective B2B email outreach.
Avoid phrases associated with spam
Certain words trigger spam filters: "free offer," "click here," "100% free," "urgent," "special promotion." In a professional B2B sales context, these phrases generally have no place, but it’s helpful to keep them in mind when writing.
Handle bounces and unsubscriptions immediately
Every bounced email and every unprocessed unsubscribe request damages your sender reputation. In a properly configured automated marketing system, bounces and unsubscribes are handled automatically, and the corresponding contacts are immediately removed from active sequences.
Include an unsubscribe link
Since February 2024, a one-click unsubscribe link has been required in all mass-sent marketing emails to Gmail and Yahoo, in accordance with new guidelines from Google and Yahoo. Beyond compliance, this is a best practice: a recipient who can easily unsubscribe is less likely to mark your email as spam.
5. Monitor your reputation using the right tools
Deliverability isn't something you set up once and then forget about. It's a metric that needs to be monitored continuously, just like your open and response rates.
Google Search Console
Google Postmaster Tools is a free tool from Google that lets you monitor your domain's reputation with Gmail. It displays your reported spam rate, your domain and IP reputation, and alerts you if there is a decline.
This is the first tool you should set up, even before launching your first lead generation campaigns.
MXToolbox
MXToolbox lets you check your entire DNS configuration (SPF, DKIM, DMARC) with a single click, test whether your IP address appears on known blacklists, and diagnose configuration issues. Running a check on MXToolbox before each new campaign helps you avoid many unpleasant surprises.
Mail-tester.com
Mail-tester.com rates your email on a scale of 1 to 10 by analyzing your technical setup, message content, and sender reputation. Sending a test email before each new campaign helps identify issues before they affect your actual campaigns.
6. Warning signs you must watch out for
Certain indicators should prompt an immediate review of your email marketing practices. They are among the key performance indicators (KPIs) essential for managing your lead generation efforts.
A sharp drop in open rates. If your open rates drop from 40% to 15% in just a few days without any changes to your target audience or message, it’s often a sign that your emails are landing in the spam folder rather than the inbox.
A bounce rate exceeding 3%. Above this threshold—which is standard in the email marketing industry—your contact list needs to be cleaned up, and your sender reputation is at risk.
Reported spam rate exceeds 0.1%. This threshold is explicitly stated in the official Google Sender Guidelines. Exceeding it triggers progressive filtering measures that can quickly render your campaigns ineffective.
No responses to a sequence that usually performs well. When a sequence that used to generate responses stops doing so without any apparent change, deliverability is often the issue.
7. Deliverability and personalization: the often-overlooked link
One thing many teams don't realize: personalizing your emails has a direct impact on deliverability. An email that's personalized enough to feel tailored to the individual generates more opens and fewer spam reports than a generic email sent to hundreds of identical recipients.
Gmail and Outlook algorithms analyze recipients' behavior to assess the quality of the emails they receive. An email that is opened, read, and replied to improves your sender reputation. An email that is ignored or reported damages it.
This is one of the reasons why large-scale personalization isn’t just a way to boost response rates. It’s also a way to improve deliverability, as explained in our article on how to automate your prospecting sequences without making them feel impersonal.
Frequently Asked Questions About Deliverability in Lead Generation
How long does it take to warm up a domain?
It takes between 4 and 6 weeks for a thorough warm-up that allows you to reach volumes of 300 to 500 emails per day. Some automated warm-up tools can speed up this process, but none of them allow you to bypass it completely without risk.
Can you use the free version of Gmail for automated outreach?
No. The free version of Gmail is limited to 500 emails per day for all purposes, and free accounts are suspended more quickly if there is unusual sending behavior. Google Workspace is the minimum recommended for professional outreach.
What should you do if your emails have already been marked as spam?
Immediately stop sending emails from that domain, identify the cause (uncleaned list, excessive volume, problematic content), correct the technical settings, clean the list, and restart a gradual warm-up. In severe cases, a new domain may be necessary.
Is deliverability different for LinkedIn?
LinkedIn has its own usage policies that limit the number of invitations and messages per week. These limits are separate from email deliverability, but the principle is the same: gradually increasing your volume and sending personalized messages reduces the risk of account restrictions.
Conclusion
Deliverability isn't just a technical issue for developers. It's a strategic component of any effective automated marketing campaign. An email that doesn't reach the inbox might as well not exist, no matter how good its content is.
Flawless DNS configuration, rigorous warm-up, mastered sending practices, and continuous monitoring: these four pillars determine the effectiveness of everything else you build in your multichannel outreach campaigns.
At Scal-IA, we always include a deliverability audit as part of the implementation of any automated lead generation system. Because a well-designed system built on a shaky foundation won’t deliver results.
