Email Blocked (or Quarantined): Common Reasons
Overview
Sometimes emails get blocked or go to your spam folder even if they are not junk. The Barracuda spam filter helps protect you from harmful or unwanted emails, but it can also stop messages that look suspicious for different reasons. This article explains why that might happen.
Getting Started
This guide explains the most common reasons a message might be blocked or quarantined by the Barracuda spam filter and how to avoid or handle those issues.
Common Reasons for Message Blocking
Barracuda blocks messages based on certain red flags in the email content or sender information.
- The sender's email address or domain is on a known spam list.
- The message contains suspicious links or attachments.
- The email has a very low reputation score or comes from an unverified source.
- The subject or body includes spam-like wording or phrases.
- The message is sent to many recipients at once (bulk email behavior).
- The email contains no text in the body, or only an image or a link, which can be flagged as suspicious.
Common Reasons for Message Quarantining
Quarantined emails are held for review instead of being sent directly to your inbox or blocked completely.
- The content seems suspicious but not harmful enough to block.
- The email score is borderline between spam and safe.
- The message contains unusual formatting or embedded images that raise flags.
- The sender has not been previously marked as trusted or safe.
- The system is unsure and flags it for your manual review.
- The message contains no written text in the body, which can look like spam or phishing attempts.
Additional Details
- You can release quarantined messages from your daily Barracuda quarantine summary email.
- You can mark a sender as "Not Spam" to prevent future filtering of their messages.
- ISS can whitelist trusted addresses or domains if needed.
- To avoid filtering, always include some plain text in the body of your emails, even if you are only sharing an image or link.