Sending limits for e-mails

Spam protection mechanisms at mailbox

Mail providers that allow anonymous registration unfortunately also attract the attention of spammers and other criminals. They either register free test accounts or misuse stolen credit card or PayPal data to open regular accounts.
mailbox therefore employs a variety of different techniques to prevent both such account openings and the sending of spam through these accounts. This is in the interest of all mailbox users, because by safeguarding the good reputation of our mail relays we ensure reliable delivery of all mails. This reduces the risk that mails sent from mailbox accounts are treated as spam by recipients.

Among other things, our systems evaluate a wide range of technical criteria when sending mails and calculate the probability of whether, for example, mass mailing is normal or whether it is a case of abuse. Factors such as the age of the account or the average mail volume of the past few days are also included in these calculations. Understandably, we cannot disclose the exact mechanisms and specific criteria in detail, otherwise spammers could adjust their behavior to their advantage.
The various indicators are therefore combined in an overall assessment. If the result shows that the probability of account abuse is high, the mail sending of this account can be temporarily blocked to protect everyone.

How many mails can I send per day?

It is not possible to say exactly how many mails an account can send per day. However, the following basic rules apply:

• An unpaid, newly registered test account allows up to 10 mails per day to mailbox addresses for testing purposes. Sending to external mail addresses is unfortunately not possible. To prevent abuse, we can only grant relatively low sending limits to unverified accounts. We ask for your understanding. If you nevertheless try to send a mail to an external address, you will receive an error message containing the note Relay access denied. As soon as a payment for the account has been received, this restriction will of course be lifted and it will be possible to send to external mail addresses as well.

• A normal private mail account can send up to 10,000 mails per day. Occasionally, one or two of the spam indicators mentioned above may trigger. In this case, a user’s mail sending will already be blocked after approx. 5,000 mails. Even users who display unusual behavior and normally send few, but suddenly many mails, should still be able to send well over 1,000 mails per day. This should be more than sufficient for private use.

• Business customers have fixed contracts with us and are easier to authenticate as account holders. The risk of abuse through the use of stolen data to pay for account openings is thereby minimized. In addition, each business customer undergoes a careful manual review by us before activation.
  Therefore, we usually allow business customers 50,000 to 100,000 mails per day.

What happens if I exceed these limits?

If you have a test account and want to send externally, this is, as mentioned, not possible.
You will then receive the error message:

"Message could not be sent to the following recipients: ..... 554 - 554 5.7.1 Relay access denied."

As soon as you have chosen and paid for a contract, your account will also be activated for external sending.
If credit has already been deposited, this message has another cause. In such a case, please open a ticket at https://support.mailbox.org.