Blocking: Domains or email addresses added to the block list are automatically blocked without undergoing spam checking.
Allowing: Domains or email addresses on the allow list are automatically forwarded to the recipient without spam checking.
When managing allowing and blocking, please note the following important rules:
- An email address cannot be on both the allow and block lists simultaneously. If an email address is added to the block list while it is on the allow list, it will be removed from the allow list.
- Entries cannot be present at both the domain group level and the domain level. If you add a new entry to the domain group block or allow list that already exists for any domains in that group, it will be removed from the domain level and categorized as a domain group entry.
- Per-recipient allow and block lists take precedence over the global allow and block lists for a domain.
- Allowed senders will bypass the SpamTitan Cloud anti-spam engine; however, emails from these senders will still be scanned for viruses and prohibited attachments.
Greylisting: Greylisting temporarily rejects all incoming emails, requiring the sending server to attempt delivery again after 5 minutes. This approach offers several advantages:
- Spammers typically do not retry sending emails, while legitimate servers will.
- The delay allows time for an IP address to be listed on Real-time Blackhole Lists (RBLs) if it is associated with spam.
While greylisting is an effective method for blocking spam, it can result in a delay of 5 to 10 minutes for legitimate emails, depending on the sending server.