The error shows you hit a limit of five emails for your SMTP configuration, which stopped the flow. This limit could come from your SMTP provider or the software you're using.
To fix it, check if you can raise the email limit in your SMTP settings or slow down the email sending rate. If it keeps happening, reach out to your provider's support for help with these restrictions.
Hello, I am in the same situation: selfhosted installation and getting the warning of 5 emails limit. Did someone find a solution? I do not think it is a SMTP limit - in the mail log there is no trace of failed connections ¯\_(ツ)_/¯ It seems more a security limit put the code of the app.