How Long Does It Take to Warm Up an Email Domain for Recruitment and HR?

Here’s a wake up call for any business planning to send emails at scale: The email domain warm-up process should not be skipped. Especially in the recruitment and HR industry.

Recruitment agencies and talent acquisition teams rely on email. A properly warmed up email domain isn’t just what ensures that messages are landing in the inboxes, it’s also what helps build trust with candidates and employers— which reduces the likelihood of being marked as spam.

In this guide, we’ll look at how long it typically takes to warm up an email domain for recruiting and HR. We’ll also be discussing best practices, the most common mistakes to avoid, and how Warmy’s tools can help simplify the process and increase your email deliverability.

Here’s why email domain warmup matters for recruitment & HR

In recruitment and HR, email is one of the main channels used for communicating with potential candidates and clients. But then here’s the issue: getting your emails to land in inboxes is not 100% guaranteed.

Poor deliverability can result in missed opportunities. Your top candidates may not see a job interview or offer if your email landed in the spam folders. Email domain warmup matters—because it’s what gets your recruitment emails seen.

Here are the key things to remember: If your emails don’t reach your intended recipients, all of the time spent sourcing or qualifying candidates can go to waste. Thankfully, there’s a solution. Warming up an email domain helps HR and recruitment teams establish a good reputation with email service providers (ESPs) like Gmail, Yahoo, and Outlook—increasing the chances of emails landing in the inbox and getting seen.

Typical warmup timelines for recruitment & HR

While the timeline may differ for warming up an email domain, here’s what worked for us. 

• For active domains with a pre-existing sending history and track record: The warmup process can take around two to four weeks. During this period, the goal is to establish credibility with various email service providers. They must get used to your domain sending emails regularly. Send only a few emails a day in your first week. The volume can be raised slowly over the coming weeks, paying close attention to engagement data. Avoid sudden spikes in email volume which could trigger spam filters.
• For new or inactive domains: Since new domains have no sending history, email service providers will need more time to get to know them. During the 4-6 week period, it’s important to monitor deliverability metrics closely. 

🔖 Relevant Reading: You can access the Warmy Research Team’s report on different email platforms and diverse domain configurations and how they affect warm-up:  The Science and Process of Warming Up Newly Created Email Domains

What influences warmup speed for recruitment emails?

How quickly or how slowly your email domain warms up depends on several key factors:

Strict compliance requirements: Similar to other highly regulated industries (like fintech), recruitment emails have strict standards to adhere to. Some legal obligations, such as data protection laws (e.g., GDPR) also affect the way inbox providers process recruitment emails.

Previous reputation issues or blacklisting. If your domain has a history of poor deliverability, spam complaints, or is included on a blacklist, your warmup process might take longer than expected. ESPs view these events as red flags, and you’re going to have to do more and better to win them over.

Erratic volume and frequency when sending. Sudden spikes in email volume (especially after an inactive period) are frequently related to spam-like behavior—which can and does influence the warm-up process. Proper email warmup needs to increase sending volume gradually and continually—always have consistent sending times.

The preference of the mailbox provider (e.g., Gmail, Outlook). Many mailbox providers, such as Gmail and Outlook, have internal filtering guidelines and volume limits for new senders. For example, new email domains may get passed a bit more freely by Gmail as opposed to Outlook that can be more vigilant. (Read more: This report from Warmy Research Team discusses what affects inbox placement speed: Cracking the Inbox Code: What Speeds Up Outlook Delivery from Different SMTP Providers?)

Content quality and engagement. Content that is high-quality and relevant means more engagement, which improves your sender rating. Conversely, unsubscribe rates, prospect feedback, and recipient report spam depend on whether your content is irrelevant, generic, and poorly written content which can increase your warmup period.

Technical setup (SPF, DKIM, DMARC). Proper technical email authentication, including SPF, DKIM, and DMARC, is a must to make sure your email is seen as safe and not considered as phishing by inbox providers. If they’re wrong or some of your records are missing, you risk getting the email flagged as spam, or maybe even rejected—another setback for your warm-up.

Best practices for warming up an email domain for recruitment & HR

Warming up an email domain for recruitment and HR purposes needs a structured approach. Here are some best practices to help you navigate the process.

Start slowly with low email volume

• Start with a handful of emails sent to a focused set of super-engaged subscribers. This slow but steady beginning will build the credibility of your domain and demonstrate to ESPs that you are a trustworthy sender.
• For recruitment teams, this means initially reaching out to a small group of candidates or employers who are likely to engage with your email content. This will boost your open rates and demonstrate to inbox providers that your email communication is wanted and valued.

Gradually increase sending volume

• After the first week or two—you can begin to gradually increase your sending volume.
• Focus on a consistent increase in email sending volume. This allows inbox providers to adjust to the rise in email activity without raising suspicions of spam or unusual behavior.
• For recruiting outreach, you will need to find a balance between the increase in volume, relevance, and personalization. As you ramp up your sending volume, segmenting your audience will help steer your emails away from the spam folder.

Focus on quality over quantity

• Sending large quantities of low-quality emails will not only slow down the warmup process. It will also harm your domain reputation in the long run.
• And for recruitment campaigns, that pertains to personalized job offers, personalized outreach, and personalized content. For example, you can include the recipient’s name, a job title, or anything specific about the position for which they are being approached.

Top 3 common mistakes to avoid during domain warm-up

There are so many things in motion. As a result, there are things that can go wrong or slow this down. Here’s what to look out for, so you don’t become one of them:

Mistake #1: Ignoring spam filters

Did you know that 47.27% of emails sent worldwide in 2024 were spam? Spam filters are one of the major obstacles to achieving great email deliverability. If you think you can ignore them during the warmup process, you’re setting yourself up for failure. ESPs use sophisticated algorithms to detect behaviors and patterns commonly associated with spammers. If your email domain setup or your content show any similar signs, ESPs may reroute your email to the spam folder—or block you right away—even if you are credible, legitimate, and mean well.

Mistake #2: Sending too many emails too fast and too soon

We understand it can be really exciting to launch an outreach campaign. However, if your domain still isn’t warm enough to handle bulk campaigns, this can raise red flags result in your emails being sent to spam. Or worse, you can end up blacklisted. Remember that time and consistency are crucial factors in email deliverability. A steady approach will build trust and improve your email deliverability in the long run.

Or worse, you might get blacklisted. But you need to be aware that time and context is everything when it comes to email delivery. It’s key to be consistent to gain trust and it’ll help your email delivery rates perniciously.

Mistake #3: Underestimating the importance of SPF, DKIM, and DMARC

Email deliverability isn’t just about writing spam-free content or sending out at gradual but steady intervals. The technical setup is also important as this provides the foundation of your email infrastructure. 

Properly configured SPF, DKIM, and DMARC records show ESPs that you are legitimate, contributing to the trust factor. The three main protocols you need to know are:

• SPF (Sender Policy Framework): Informs recipients’ servers that the email you sent is really allowed to send on behalf of your domain
• DKIM (DomainKeys Identified Mail): Attaches a digital signature to each email to verify it wasn’t tampered with along the way
• DMARC (Domain-based Message Authentication, Reporting & Conformance): Connects SPF and DKIM and tells or instructs the receiving server what to do should an en email fails to pass authentication checks (Read more: Don’t Let Your Emails Get Spoofed: How a DMARC Generator Helps)

Missing records or improper configuration of these settings means there’s a bigger chance of your emails being flagged as suspicious or being rejected outright. Unfortunately, many recruiters overlook these settings, leading to long delays in the warmup process or long-term issues like poor overall deliverability.

How do you know if your email warmup is succeeding or not?

As you go on your warmup journey, you will need to assess if what you’re doing is successful or not. Regular check-ins. Here is how you can accurately track your domain warming progress.

1. Keep an eye on your open rates, click-through rates, and other metrics. 

The more that your recipients interact with your emails, the better it is for your brand and car. High open rates means your emails are most likely landing in the inbox. Since they are seen and opened, your subject lines may also be effective. A high click-through rate means your email is composed in a way that drives your recipients to act. 

🔖 Relevant Reading: Email Deliverability Benchmarks for Recruitment & HR

2. Use deliverability tools for real-time insights. 

Email deliverability tools can provide an easier way to access insights into how your email warmup is going. For example, tools like Warmy.io offer features like inbox placement tests, which can show where your emails are landing (inbox or spam folder).

They can be useful to monitor domain health and troubleshoot blacklisting issues. These insights are valuable during the warmup process so you can resolve them before they affect your actual recruitment email campaigns.

3. Identify and address early problems. 

Study the metrics and insights and match them to corresponding issues and solutions. For example: High bounce rates = technical issues = check SPF, DKIM, and DMARC. Here’s another example: Low open rates = landing in spam or bad subject lines = dial down on sending volume until your open rates show constant increase or conduct A/B tests on subject lines. 

How Warmy helps recruiters succeed in email warmup

Warmy was designed to automate the warmup process and ensure its success. Instead of recruiters and HR professionals sending emails manually, tracking open rates manually, and thinking of strategies—Warmy does the job. 

It addresses the unique challenges faced by recruitment professionals, ensuring safe, efficient, and effective email outreach to candidates and employers. This means HR teams can focus on building trust with their recipients while avoiding email deliverability issues.

Here are just some of the features and tools from Warmy that make it the perfect email warmup companion for recruitment and HR teams.

AI-driven warmup process with customizable features