Often when testing on development environments you will interact with a feature that involves sending email. This can be a password reset, email confirmation, etc.
If you're using a 3rd party email delivery service and you're running lots of integration tests it's possible that your email reputation will decrease. This can be avoided by using a virtual SMTP instead of using up your reputation and email limits for integration tests.
Mailisk supports this via it's SMTP which can be used to send emails to any valid Mailisk address within the same namespace. There are no outbound limits to using SMTP, received emails will go normally towards your monthly limit.
To see your SMTP credentials for a specific namespace go to your namespace and open the additional settings:
For examples on how to use SMTP see the NodeJS section.