Glossary of MailOut
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Definitions
Section titled “Definitions”Authorized sender
Section titled “Authorized sender”An authorized sender specifies the credentials used with STACKIT MailOut to authenticate with the SMTP endpoint to send emails.
Sending domain
Section titled “Sending domain”The domain name used for outgoing emails (in the FROM address) that a customer configures and authenticates with MailOut via DNS records (SPF, DKIM). It’s the identity that builds up sender reputation over time.
Hard bounces
Section titled “Hard bounces”A permanent delivery failure – the recipient address doesn’t exist, the domain is invalid, or the mailbox was closed. These addresses should never be retried and get suppressed automatically by MailOut for future messages. STACKIT MailOut users can
Soft bounces
Section titled “Soft bounces”A temporary delivery failure – full mailbox, server timeout, message too large or greylisting. MailOut usually retries 3 times before giving up.
Bounce rate
Section titled “Bounce rate”Is the amount of hard and soft bounces per sending domain as a percentage of sent messages. This is a key health metric for STACKIT MailOut users and should be monitored.
Sender reputation
Section titled “Sender reputation”The sender reputation is a score (per-IP and per-domain) that mailbox providers use to decide whether to inbox, spam-folder or even reject mails.
Suppression list
Section titled “Suppression list”In the event of a “hard bounce” that occurs with a specific message sent to a recipient, the recipient of that message is added to the block list of the sending domain from which the message originated. MailOut users are able to administer the suppression list of their sending domain. It is good practice to use the suppression list to clean up your own sender lists.