You may have received a notification that a message could not be sent to one or more recipients. Sometimes this is a one-off or temporary problem, but in some cases it can be a permanent problem with an email address. We always advise you to look carefully at the reason given. In this article, we will explain to you what the possible causes are and what you can do about it.
You can find the possible cause of a failed send attempt in the event in the message details of the message.
Hard bounces
The message details in MICE shows that the message has been rejected with the reason "rejected: hard-bounce". In most cases, this indicates a permanent problem with an email address. Email addresses with this message are usually quarantined immediately. Some common reasons are:
The email address does not exist.
The receiving mail server has completely blocked delivery.
Delivery to the specified email address has failed and resulted in a soft bounce several times in a row.
What can you do about this?
Check with the recipient whether the email address is correct and correct it if possible. If the email address is correct, it is advisable to try anyway with another email address.
Soft bounces
The message details in MICE Operations show that the message has been rejected with the reason "rejected: soft-bounce". This usually indicates a temporary problem. The mail system then tries to redeliver the e-mail several more times. If delivery of the e-mail continues to fail, the e-mail address will still be quarantined and marked as hard bounce. Some common reasons are:
Mailbox is full
Mailbox is inactive or there are problems with it
Receiving mail server is not responding or is offline
Receiving mail server is having problems processing mail
Domain name does not exist
Email message is too large
Email message is blocked based on content
Email message does not comply with receiving mail server policy
What can you do about this?
Some of these problems are temporary. The mail server does several attempts to send the email again later. Some problems are not resolved quickly enough, so the email address is quarantined anyway. If the problem persists, it is advisable to contact the client or try with another email address.
Message is delayed
You may see that a message has been 'delayed' in the message details. Delayed means that the receiving mail server has sort of accepted the message, but reports back that the message is delayed. From then on, we have no visibility on actual delivery. To be sure, check with the recipient whether the message has been received (also let them check the spam box).
Quarantine
In the event of significant problems, email addresses are quarantined. This means no emails will be delivered to that address for 7 days (approximately). For hard bounces, this happens immediately, for soft bounces after a number of unsuccessful attempts. An address can also be quarantined in the event of a spam alert.
Quarantine ensures that the mail system is not unnecessarily burdened with email addresses that do not work and prevents reputation damage, which could make delivery of other emails less successful.
If an address is wrongly quarantined, you can report this to us. The email address can then be released again in the meantime.