Number of malicious emails the SIA blocked in 2019, 2020 and 2021
Published 17 February 2022
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This publication is available at https://www.gov.uk/government/publications/number-of-malicious-emails-the-sia-blocked-in-2019-2020-and-2021/number-of-malicious-emails-the-sia-blocked-in-2019-2020-and-2021
1. Request
The total number of malicious emails blocked by your organisation over the last 3 calendar years (2021, 2020, 2019) broken down by year and categorised accordingly.
2. Response
I confirm that the SIA holds part of the information that you have requested.
Mimecast email data and file retention is for a short, set period of time. We are therefore only able to provide a breakdown of the malicious emails blocked by the SIA for the reporting period 20 January 2021 to 19 January 2022, which can be found below.
| Rejection Types | Count |
|---|---|
| Invalid Recipient Address | 59,504 |
| IP Found in RBL (real-time blackhole list) | 41,836 |
| Anti-Spoofing Lockout | 4,249 |
| Manual Envelope Rejection | 3,517 |
| Spam Signature Detection | 2,57 |
| Manual Header Rejection | 1,343 |
| Message Size Limit Reached | 832 |
| DMARC (Domain-based Message Authentication, Reporting, and Conformance) Reject | 564 |
| Envelope Rejected | 334 |
| Anti-Spoofing Header Lockout | 195 |
| Virus Signature Detection | 128 |
| Total | 114,659 |
[Reference: FOI 0318]