Using the same domain or IP address for cold and warm email campaigns significantly risks sender reputation and deliverability. Poor cold email practices, such as sending to unverified lists, ignoring unsubscribe requests, generating spam complaints, or failing to adhere to anti-spam policies, can lead ISPs and mailbox providers to flag the domain/IP as a source of spam. This results in legitimate, 'warm' emails being blocked, sent to the spam folder, or even resulting in blacklisting. While subdomains offer limited protection, complete separation via different domains and IP addresses is the recommended best practice to protect the primary domain's reputation. Addressing deliverability issues requires stopping the harmful cold email practices and actively rebuilding the sender reputation. Monitoring engagement, maintaining clean lists, and adhering to email marketing best practices are also crucial.
8 marketer opinions
Sending cold emails using the same domain or IP address as your 'warm' emails can significantly harm your sender reputation and deliverability. Poor cold email practices, such as sending to unverified lists, ignoring unsubscribe requests, or generating spam complaints, can lead ISPs to flag your domain as a source of spam. This results in your legitimate emails being blocked or sent to the spam folder. While separating streams by subdomain offers limited protection, using entirely separate domains and IP addresses is recommended to avoid damaging your primary domain's reputation.
Marketer view
Email marketer from Sendinblue Blog explains that using the same domain for cold and warm emails can damage your sender reputation if your cold emails have low engagement (opens, clicks). This can lead to your warm emails being marked as spam.
27 May 2021 - Sendinblue Blog
Marketer view
Email marketer from Email Marketing Forum explains that if you're blasting out cold emails and people are marking them as spam, that's going to hurt your overall domain reputation, no matter how 'warm' your other emails are supposed to be.
27 Jul 2024 - Email Marketing Forum
4 expert opinions
Cold email practices can severely impact the deliverability of legitimate 'warm' emails if they share the same domain or IP address. Spam complaints from cold emails can degrade sender reputation, leading to all emails from that domain going to spam. The best practice is to completely separate cold email activities onto a different domain and IP, and to avoid mentioning the primary domain in cold email communications. Fixing reputation requires stopping the problematic cold email practices.
Expert view
Expert from Spam Resource explains that if cold emails generate spam complaints, even legitimate 'warm' emails sent from the same infrastructure (domain/IP) will suffer deliverability issues, potentially landing in spam folders or being blocked outright.
19 Jun 2021 - Spam Resource
Expert view
Expert from Word to the Wise explains using a separate domain and IP address for cold email is the best practice to avoid damaging the reputation of your primary domain used for legitimate email. Shared infrastructure risks deliverability for both streams.
20 Feb 2022 - Word to the Wise
5 technical articles
Sending unsolicited emails, including cold emails violating anti-spam policies, negatively impacts sender reputation and deliverability. This can lead to emails being marked as spam, blocked, or IP/domain blacklisting, hindering the ability to send legitimate emails. High complaint volumes significantly contribute to filtering and blocking based on reputation. Adhering to best practices, obtaining consent, and avoiding spam-like content are crucial for maintaining a positive sender reputation.
Technical article
Documentation from Microsoft 365 documentation explains that sending unsolicited commercial email (spam) can lead to IP address and domain blacklisting, negatively affecting your ability to send legitimate email.
18 Oct 2021 - Microsoft 365 documentation
Technical article
Documentation from M3AAWG shares that volume of complaints impacts sending reputation. If people complain a lot they will filter or even block the mail based on volume and reputation.
30 Mar 2025 - M3AAWG
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