I have been using Local Wp for a long time and have never had any problems - but today I was working on a site with a supscription service and I had to test if the mails were correct - so I checked my mailhog to see them - nothing - but suddenly a customer contacted me cause she had gotten the mail which should have been contained to my local mac.
Troubleshooting Questions
This should be possible since the local wp is a closed environment - so all mails should be inside mailhog.
Are you using a transactional mail service (e.g. Sendgrid, SES), or SMTP server? If you have one of these configured in your environment (typically via a plugin), it will still try to send out using that mail service.
Looking at the description from the plugin that you referenced (Newsletter, SMTP, Email marketing and Subscribe forms by Sendinblue – WordPress plugin | WordPress.org), it would appear that with it enabled, emails will be sent out through Sendinblue’s transactional email servers. I suspect that it’s sending ALL emails out that way, not just those related to the newsletter functionality. Here’s what it says on that page:
Transactional emails – The wp_mail() function automatically uses Sendinblue’s SMTP for enhanced deliverability and tracking
Automatic replacement of default SMTP when you use wp_mail function
I would suggest disabling that plugin on your development environment, or at least disabling the sending of emails through the Sendinblue servers – there appears to be a checkbox for this on the plugin’s page in the WP admin.
