We have a server (Ubuntu 12.04) that we use mostly for development purposes. There are about 50 vHosts created in Virtualmin that I would like to completely disable the ability to send email.
Under 'Edit Virtual Server' > 'Enabled features' there is the checkbox for 'Mail for domain enabled?', but the description for that states 'will be configured to accept email', and does not refer at all to sending email.
Is there any way to disable sending emails? Then I can enable it only when the developer is actually working on an email-related problem? (We had an issue where someone started sending spam off one of these accounts).