Why you should warm up a new sender domain

Why you should warm up a new sender domain

Marketers often use a new sender domain under the following circumstances:
  1. They purchase a secondary sender domain to send more emails
  2. Their company is completely new to email marketing
  3. They've planned to use a sender domain that was used sparsely
When you send a huge number of emails from a new or sparsely used sender domain, mailbox providers will be suspicious about your emails and might flag them as spam and deny inbox placement. To prevent this, you must warm up your sender domain.

What is domain warmup?

Domain warmup is the process of building a positive reputation with inbox providers, which will help in achieving inbox placement and in avoiding email throttling and email quarantining.

What if I don't warm up my sender domain?

Mailbox providers are tirelessly working to provide a safe email experience for their users. When you send emails from a new sender domain that is not warmed up, your marketing efforts might be in vain due to the following:

Your emails will be rejected

Mailbox providers have strict spam guidelines and will often reject emails that are sent from a sender domain that has negative reputation or no reputation. When you send emails from a sender domain that is not warmed up, your emails may get rejected.

Your emails will be quarantined

Since spammers mostly use new sender domains to blast emails, when mailbox providers receive emails from sender domain that has no reputation, or when they receive emails that resemble spam, they will queue those emails in their server and scan them for potential threats. 
If you send emails without warming up the sender domain, your emails will be flagged as suspicious and will be stored in mailbox provider's server and scanned for threats.

Your emails will be classified as spam

Mailbox providers offer inbox placement based on sender domain's reputation. If you send thousands of emails from a new sender domain which has no reputation, your emails will be marked as spam.

Email engagement and ROI will be affected

When emails don't land in the inbox or when emails are flagged as suspicious, your recipients will be less likely to open them or click on anything inside, thus email engagement will be seriously affected. Lack of engagement will obviously lead to a decrease in your ROI.

Your domain will be blacklisted

When a considerable number of your emails are marked spam, your sender domain will earn a negative reputation. If the sender domain keeps earning a negative reputation, there are chances for it to get blacklisted.


Mailbox providers like Gmail, Outlook, Yahoo, and Zoho Mail consider domain reputation to offer inbox placement. If you are planning to use a new sender domain, you must send a considerable number of emails to build a healthy reputation.

Also, when you are planning to send high volume of emails, it is advisable to split the total number of emails and send them either at a regular interval or on a daily basis and stretch the time duration as much as possible to avoid email throttling.

If a considerable number of your contacts use Gmail, you can use the Google postmaster tool to identify the reputation your sender domain has earned. For other mailbox providers, you can run a test email campaign with your test accounts and use the inbox placement result to identify the reputation your sender domain has earned.

Though domain warmup may sound complicated, it is an effective practice with which you can improve email deliverability and email engagement.

If you have any questions, feel free to reach out to us at support@zohocampaigns.com. Our deliverability experts will be more than happy to answer them.

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