The consensus is that while Mailosaur, when used correctly, aims to simulate real user behavior without negatively impacting deliverability, sending to invalid, non-existent, or spam trap addresses—even for testing purposes—can harm sender reputation over time. Experts recommend caution regarding excessive test emails, especially via Gmail, and emphasize maintaining good list hygiene, regular validation, and monitoring bounce and spam rates to mitigate risks. Address harvesting should be avoided.
8 marketer opinions
The impact of Mailosaur test email addresses on email deliverability is complex. While Mailosaur itself, when used correctly, aims to simulate real user behavior without triggering spam filters, sending emails to invalid, non-existent, or spam trap addresses – even for testing purposes – can negatively affect sender reputation over time. This is primarily due to increased bounce rates and potential identification as a sender with poor list hygiene. Therefore, maintaining a clean and validated email list and utilizing appropriate testing practices are crucial to mitigating these risks.
Marketer view
Email marketer from Email on Acid shares best practices for testing email campaigns. While testing is essential, it's important to use real email addresses or testing tools like Litmus or Email on Acid itself to avoid potential deliverability issues associated with spam traps.
13 Jan 2024 - Email on Acid
Marketer view
Email marketer from Gmass explains that the quality of your email list is critical for maintaining a good sender reputation and deliverability. Sending to invalid or spam trap email addresses can increase your bounce rate and damage your reputation.
1 Jun 2022 - Gmass
5 expert opinions
While using Mailosaur for testing may not cause long-term deliverability issues, experts advise caution. Excessive test emails, especially when sent rapidly or via Gmail, can trigger mail delays and potential blocks. Mailosaur itself is likely not directly tied to major reputation engines, minimizing immediate damage. However, practices like address harvesting, which can lead to invalid addresses and spam traps, should be avoided to maintain good deliverability and feedback loop health.
Expert view
Expert from Email Geeks shares that mailasaur is hosted on Google Cloud and likely not tied to any big reputation engine, minimizing potential reputation damage.
14 Sep 2022 - Email Geeks
Expert view
Expert from Email Geeks responds that the test emails could cause problems and suggests temporarily pausing sending.
13 Feb 2022 - Email Geeks
5 technical articles
Email deliverability is significantly affected by the quality of email lists and the practice of sending to test addresses. Documentation from various sources emphasizes that sending to invalid, bouncing, or spam trap email addresses, including those used for testing, can negatively impact sender reputation and lead to deliverability issues. Maintaining good list hygiene, regular validation, and monitoring of bounce and spam rates are critical for ensuring successful email delivery.
Technical article
Documentation from SendGrid answers that high bounce rates, often caused by sending to invalid or test email addresses, can negatively affect your sender reputation. Monitoring and managing bounce rates is crucial for maintaining good deliverability.
14 Feb 2025 - SendGrid
Technical article
Documentation from Google Postmaster Tools explains that high spam rates, often resulting from sending to outdated or test email addresses, can significantly harm your sender reputation and lead to deliverability issues. Monitoring spam rates is crucial for identifying and addressing these problems.
3 Aug 2022 - Google Postmaster Tools
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