10 Common Email Warm-up Mistakes to Avoid in 2025

The whole point of warming up your email account is to build or repair its sender reputation so your messages reach the inbox.

But I have seen many times that email warm-up can have the opposite effect!

Instead of landing in the inbox, your emails may end up in spam or even get your account blacklisted.

I have seen countless posts on Reddit and LinkedIn of people who faced this exact problem, and there is a real chance you can also experience it if you are not careful.

In this blog, I’ll share 10 email warm-up mistakes that can ruin your warm-up efforts and even show you how to avoid them.

P.S. You don’t have to worry about most of these mistakes if you’re using a reliable warm-up tool like TrulyInbox.

Top 10 Email Warm-Up Mistakes You Should Avoid in 2025

I have been experimenting with email deliverability for a long time, and during that time, I found these 10 often-overlooked but avoidable warm-up mistakes:

1. Not Authenticating Your Email Accounts
2. Sending Too Many Emails From the Start
3. Using a Shared IP Address
4. Warming Up Inconsistently
5. Emailing Random Accounts
6. Not Cleaning Your Email List
7. Not Monitoring Your Sender Reputation
8. Using Spammy Words
9. Not Personalizing Warm-up Emails
10. Not Creating Conversational Threads

1. Not Authenticating Your Email Accounts

The first thing you should do before starting your email warm-up is setting up your authentication records.

If you miss this step, you’re email accounts will probably get blacklisted even before you start reaching out to your prospects.

There are three authentication protocols, and here’s what they do:

• Sender Protocol Framework (SPF): This protocol will tell Email Service Providers (ESPs – Gmail, Yahoo, etc) that your emails are coming from an authorized server.
• Domain-Keys Identified Mail (DKIM): Adds a digital signature to your emails to show ESPs that it has not been tampered with when in transit. This is very important to show your email’s integrity.
• Domain-based Message Authentication, Reporting and Conformance (DMARC): This is the final security checkpoint. You can tailor your DMARC policy to tell ESPs how to handle emails that fail SPF and DKIM checks.

If you are planning on using your email accounts for cold emails or outreach, I suggest setting up all three authentications the moment you get your hands on your new email account.

If you want to know how to set up your records correctly, I’ve written a step-by-step guide on setting up SPF, DKIM, and DMARC that walks you through the process.

2. Sending Too Many Emails From the Start

This is the most common email warm-up mistake I see many cold emailers and marketers make.

This is the fastest way to destroy your sender reputation before it has a chance to build.

If you start sending a high volume of emails right away, email service providers (ESPs) like Gmail, Outlook, etc., will flag you for suspicious behaviour.

The Solution: Start by sending just 2 or 3 emails a day. Then gradually increase your sending volume by about 20 percent each day till you reach the recommended limit.

• For cold emails, the recommended limit is about 50 emails per day per account.
• And for email marketing, you can go up to about 100 emails per day per account.

3. Using a Shared IP Address

With a shared IP, you could be sharing your email infrastructure with spammers, bulk emailers, or businesses with poor sending practices.

So, their mistakes can hurt your sender reputation, even if you’re doing everything right.

So what’s the fix?

Use a dedicated IP address.

Alternatively, you can also go for a very reputable email provider that actively monitors senders and removes users who use bad sending practices.

This way, you can still use a shared IP, keep costs low, and get high deliverability.

4. Warming Up Inconsistently

The goal of email warm-up is to prove to Email Service Providers (ESPs) that you’re a trusted sender, not a bot spamming their users with irrelevant content.

So, if you send 10 emails today, 20 tomorrow, then none the next day, and suddenly 10 again, you’re sending mixed signals to the ESP.

This inconsistency will hurt your sender reputation.

I highly recommend that you follow a consistent email warm-up schedule. It will increase your inbox placement rate and boost your sender reputation.

Here’s my guide on how you should properly warm up your domains before outreach.

5. Emailing Random Accounts

To whom you send emails matters a lot during the warm-up stage.

If you’re sending emails to random, unverified, or inactive accounts, you’re making a huge mistake!!!!

ESPs will monitor how recipients interact with your emails.

High email bounces, unopened emails, or spam reports can seriously damage your sender reputation.

So when doing warm-up manually, you need B2B email accounts (preferred) with good sender reputation and start conversations—not just send one-way emails.

This is why I recommend using an automated email warm up platform, as they can do all the heavy lifting for you.

6. Not Cleaning Your Email List

Throughout my experience in outreach, I’ve noticed that some users obtain email lists just to send warm-up emails—and that’s where they go wrong.

If you’re sending warm-up emails to unverified, inactive, or low-quality addresses, you’re doing more harm than good.

Your emails may bounce, go unopened, or get flagged as spam, etc., and all this will damage your sender reputation.

The Fix I Suggest: Send your warm-up emails to people you know well and ask them to:

• Open your emails as soon as they land in their inbox.
• Reply naturally to create engagement (even a short response works).
• Mark your emails as important or move them out of the spam folder if they land there

7. Not Monitoring Your Sender Reputation

One scenario I’ve often observed in email warm-ups is that users send emails and just hope for the best—thinking that after three or four weeks, they’re good to go for their cold email or outreach campaign.

But here’s the reality: Email warm-up isn’t just about waiting—it’s about actively monitoring your sender reputation to ensure everything is going smoothly.

If you don’t track your sender reputation, you could be wasting weeks on a failed warm-up process without even realizing it. 

Here’s what you should do to avoid this 👇

Use Google’s (free) Postmaster Tools to monitor your sender and domain reputation, and you can also check for spam complaints.

If you see a dip or spike in these metrics, you’ll have to take corrective action.

8. Using Spammy Words

When you use spammy or salesy phrases like “Deal,” “Discount,” “Buy Now,” and similar trigger words in your warm-up emails, you send red flags to spam filters.

ESPs scan subject lines and body content for these terms, and repeated use can get your emails routed to the promotions tab or spam folder, even during warm-up.

The Solution: Keep your warm-up emails simple and conversational.

Use neutral language instead of hard-sell words, and focus on making the email look like a genuine message rather than a marketing pitch.

Also Read: How to Stop Emails From Going to Spam?

9. Not Personalizing Warm-up Emails

Another common mistake I’ve seen (and even made myself) is that users send generic-sounding emails during email warm-up.

ESP spam filters are smart!

If they notice a set pattern of emails being sent from your account, they might mistake you for a bot and mark your email account for malicious activity.

And what does that mean?

You guessed it: low sender reputation, low deliverability.

So, and I can’t emphasize this enough: always personalize your emails, even during the warm-up phase!

Also Read: Cold Email Personalization: All You Need To Know in 2025

10. Not Creating Conversational Threads

If you want to quickly build trust with ESPs and strengthen your sender reputation, you need to make your warm-up emails look like real conversations instead of one-way blasts.

Here’s what you can do: Create threads by replying to your own warm-up emails or having a colleague respond to your emails.

This mimics natural interaction and helps your domain get treated as a legitimate sender.

Manually doing this is a lot of hassle, so I recommend using an automated email warm-up tool to handle the replies for you and save time.

Next, I’ll show you how you can easily avoid these silly mistakes.

How to Easily Avoid Email Warm-Up Mistakes?

Now that we’ve gone through all the mistakes you can possibly make in email warm-up, I know what you’re thinking:

It’s one thing to understand where you might go wrong, but another to successfully avoid all the mistakes.

I hear you: avoiding all email warm-up mistakes can be very challenging if you do warm up manually!

But by automating it with the right email warm-up platform, you can easily avoid all these silly mistakes.

How Does An Email Warm-Up Tool Work?

• The tool automatically starts with a very low number of emails and steadily increases the volume each day to mimic natural growth.
• It creates replies between real inboxes or networks of inboxes to simulate real conversations, which helps improve engagement signals.
• By combining gradual sending, real replies, and authentication, the tool sends consistent positive signals to Gmail, Outlook, and other ESPs.

All of this happens automatically in the background, so you do not have to manually send and reply to dozens of emails every day.

Let me show you some of the most reliable platforms if you want to try one for your business.

3 Best Tools to Help You Avoid Email Warm-up Mistakes

After testing multiple email warm-up tools, I picked three that stand out for preventing mistakes and improving deliverability.

1. TrulyInbox
2. Warmup Inbox
3. Warmy.io

1. TrulyInbox

Deliverability Rate: 98%

TrulyInbox is an effective email warmup tool that is compatible with almost every top ESP out there.

It’s also very easy to use: you can be on your way to high email deliverability in less than two minutes!

Plus, TrulyInbox puts you in charge of all critical email warm-up decisions. This includes:

• How many emails you want to send
• How many replies you want to receive
• How you want to ramp up email volume

The best part about TrulyInbox is that it allows you to connect an unlimited number of inboxes for warm-up, at no additional cost!

Pricing (Billed Annually):

You’ll find TrulyInbox to be very cost-effective when compared to many warm-up platforms.

• Starter: $22/month
• Growth: $59/month
• Scale: $142/month

Check out the pricing page to know more!

2. Warmup Inbox

Deliverability Rate: 95%

Warmup Inbox offers comprehensive email warmup services through its network of 30K+ real email accounts.

All you need to use Warmup Inbox’s warmup services is an email account with SMTP credentials. Plus, it also works with most of the best ESPs on the market.

One thing I noticed that makes Warmup Inbox stand out from the rest is its multilingual warm-up feature.

So, if you want to warm up your email account to send outreach emails to prospects in emerging markets, Warmup Inbox could be your ideal option!

Pricing (Billed Annually):

One downside to Warmup Inbox is that it charges you separately for every inbox you want to warm up.

Here’s a quick look at the plans it offers:

• Basic: $15/month/inbox
• Pro: $49/month/inbox
• Max: $79/month/inbox

3. Warmy.io

Deliverability Rate: 94%

Warmy.io provides a host of warm-up capabilities through real, human email accounts.

It also excels at generating warmup emails personalized to the recipient. This massively increases the chances of good email warmup results.

One thing I noticed about Warmy.io is that it offers topic-specific email warm-up.

So, you can select keywords depending on your industry, and Warmy.io will generate warm-up emails around that topic. 

Pricing:

Warmy.io takes a volume-based approach to pricing.

So, if you need to warm up more than one email account, the costs can multiply exponentially!

Warm up Your Email the Right Way!

Email warm-up can be a challenging process. Even simple mistakes and oversights can cost you dearly.

The best way to avoid these mistakes? Automated email warm-up.

Now all you have to do to improve the sender reputation of your new email accounts is pick the right email warm-up tool.

I have shared three of the best tools I have tested below that make the process simple and help you avoid common pitfalls.

If one of them catches your eye, take a free trial and see if it fits your workflow.

I personally recommend trying TrulyInbox as it is cost-effective and very easy to use.

Happy warm-up!

Email Warm Up Mistakes: FAQs

1. How is email warm-up helpful?

In my experience, email warm-up can help you in two ways. First, it allows you to quickly boost the sender reputation of your new email account. Second, it can help you repair the sending reputation of an old account you might have used for email outreach or cold emails.

2. How does email warm-up work?

Email warm-up is a simple strategy whose aim is to boost the sender reputation of email accounts.

Here’s what you need to do to conduct an email warm-up:

• Set up your email and authenticate the security credentials
• Start sending a small number of emails to verified accounts with a high sender reputation
• Maintain conversational threads and gradually ramp up the daily sending volumes
• Keep the maximum number of emails to 50/day
• Monitor your sender reputation to verify that the email warm-up is increasing your sender reputation

3. Can I manually warm up my email accounts?

Yes, you can manually warm up email accounts by engaging with other email accounts that enjoy a high sender reputation.

However, in my experience, manual email warm-up can be a very tedious process. The easier approach that has always worked for me is to automate the entire process through an email warm-up tool.

While it requires some initial investment, it guarantees results and takes guesswork out of the process!

4. Is using an email warm-up platform the only way to avoid warm-up mistakes?

In my opinion, yes: using an email warm-up platform is the only way to (for sure) avoid all the warm-up mistakes.

That’s because the warm-up tool sticks to very precise instructions that you provide: it’ll send a set number of emails, receive replies, and boost your sender reputation within weeks!