Why should you avoid using domains you don't control for email testing?

Marketer from Email Geeks explains more to the point, don't use a domain you don't control. You have no idea what the implications may be, or how that may change in the future. Is that more clear?

Email marketer from Litmus cautions against using disposable email services for testing as they often have poor reputations. Their use can affect your deliverability testing results.

Marketer from Email Geeks shares that sending emails to `example.com` (or any domain you don't own) reminds him of when Microsoft had to step in and buy `corp.com` because people used the domain in Active Directory without thinking about what permissions they were delegating.

Email marketer from Neil Patel explains that using domains you don't control can harm your sender reputation. If those domains are blacklisted or have poor engagement, it can negatively impact your deliverability.

Marketer from Email Geeks advises against using anything you don't control, including Gmail, Hotmail, Yahoo, `example.com`, `yopmail.com` for testing.

Email marketer from Reddit warns that using domains you don't control introduces potential security risks. If those domains are compromised, your test data could be exposed.

Email marketer from Gmass explains that proper sender authentication (SPF, DKIM, DMARC) is crucial for deliverability. You need control of the domain to set up these records.

Email marketer from StackOverflow mentions that using external domains pollutes your testing metrics. It's hard to get accurate results if you're not in full control of the environment.

Email marketer from Sendinblue shares that using a dedicated IP address and domain allows you to build a positive sender reputation. This is impossible with domains you don't control.

Email marketer from Campaign Monitor shares that setting up a separate test domain ensures that testing issues won't affect your main domain's reputation. Using domains you don't control defeats this purpose.

Email marketer from SparkPost explains that using shared or free domains can lead to deliverability issues. It's better to use a dedicated domain that you manage.

Email marketer from Mailjet shares that using domains you don't control for testing can damage your brand reputation. Deliverability tests should use infrastructure you own and control.

Email marketer from Email On Acid responds that you lose control over crucial deliverability factors when using external domains. You can't manage SPF, DKIM, or DMARC records.

Expert from Word to the Wise explains that you should avoid testing and list bombing using domains you don't control, because that sends the wrong kind of signals. Even if you think you are doing it correctly, some automated abuse systems will misinterpret the signals and think you are a spammer.

Documentation from RFC Editor states that `example.com`, `example.net`, `example.org` are reserved domain names. Using these for testing can lead to unpredictable results, as their handling might change.

Documentation from Microsoft explains that using domains without proper authorization can cause issues when integrating with Active Directory. Specifically referencing the `corp.com` incident, where unauthorized usage caused serious problems.

Documentation from MXToolbox explains that you need control over DNS records (SPF, DKIM, DMARC) for accurate deliverability testing. You can't modify DNS for domains you don't own.

Documentation from DMARC.org states that implementing DMARC on your sending domain protects it from spoofing and phishing. You need full control of the domain to implement DMARC effectively, something you can't do for domains you don't own.