**Razor** and **Pyzor** are two databases that store the *checksums* (signatures) of patterns known to have generated SPAM. To keep it simple, here is an example:

1. A user sends a mass mailing campaign whose message includes the phrase: *"Buy stolen watches"*.
2. A high percentage of recipients click the **"This is SPAM"** button in their email client, which causes that email to be analysed by several external auditors, also known as blacklists.
3. These auditors extract a checksum and determine that the phrase *"Buy stolen watches"* is the trigger.
4. From that moment on, every email containing that checksum will be flagged as SPAM.

## How do they differ?

- **Razor** is fed by Cloudmark's database, which has a huge global footprint: among others, they handle email for numerous government organisations. [More details about Razor here](https://cwiki.apache.org/confluence/display/SPAMASSASSIN/UsingRazor).
- **Pyzor** is fed through *honeypots*: bait email accounts created with the sole purpose of flagging as SPAM every message they receive. [More details about Pyzor here](https://cwiki.apache.org/confluence/display/spamassassin/UsingPyzor).

They collect checksums in different ways, but their functionality is essentially the same.

:::info
In short: if an email is flagged as SPAM by a Razor or Pyzor rule, **the reason is the content of the email itself**.
:::

## Why was the rule triggered?

Unfortunately it is not possible to find out the exact reason, but it is most likely one of these:

- The sender or the recipient has sent SPAM in the past.
- The sender's or recipient's entire domain has sent SPAM in the past.
- The subject line contains text that has been flagged for generating SPAM before.
- The body contains phrases or patterns that have generated SPAM in the past.

## Recommendations if your emails trigger these rules

- If it is a reply or a forwarded message, **remove all content that is not relevant** to the conversation. Keep only your reply: quoted content is a common cause of antispam triggers.
- **Send the email in plain text, without HTML.** This avoids most of the checksums associated with HTML markup.
- Try **changing the subject** of the email.
- Try **sending the same email to a different recipient** to rule out a problem with the recipient themselves.
- Try **sending the same email from webmail**.