If you get a notification from us that huge mail activity was caught to be done by your account, you must make an immediate arrangements to resolve the problem. That includes stopping the mail activity in case you have a big newsletter or bulletin sending more messages than we allow. We have limits regarding the amount of e-mails you can send per hour. You can read more about those limits in our Terms of Service.
If you are not aware how the messages were sent via your account then your account was compromised and used by hackers to send SPAM. If the messages were sent via an account of your customer, you must contact him to resolve the problem immediately. Please note that our services cannot be used to send thousands of messages as that will cause load problems on the server. You can send more messages on our VPS plans.
Mail activity problems must be resolved within 24 hours once you receive a notification from us. Accounts which get involved in huge mail activity multiple times are subject of permanent suspension.