Many contact-form or membership plugins use the
wp_mail method. With Mailster you can hijack the function and use the Mailster delivery options to send third party mails.
On the General tab in the settings you can find three options:
Do not use Mailster for outgoing WordPress mails
This option will bypass the functionality and uses your standard delivery method defined by either your server or another plugin.
Use Mailster for all outgoing WordPress mails
You can use this option to overwrite the
wp_mail function with a Mailster alternative. This will also use all settings from the delivery tab.
Use only the template for all outgoing WordPress mails
While this option is similar to the first one it uses the selected template and injects the message your use in the
wp_mail method. Use this method if you have problems with third party plugins not delivery your emails.