From Wikipedia, the free encyclopedia

The GTUBE ("Generic Test for Unsolicited Bulk Email") is a 68-byte test string used to test anti-spam systems, in particular those based on SpamAssassin.[1] In SpamAssassin, it carries an anti-spam score of 1000 by default, which would be sufficient to trigger any installation.

The contents of the string are as follows:


and should be placed in the message body of an RFC 5322 compliant email message, without any line breaks or whitespace.

Checksums[2] for the string (68 bytes, no trailing newline) are as follows:

Hash type Value
CRC32 dfdf8070
MD5 6a684e1cdca03e6a436d182dd4069183
SHA1 c13086867f444d503829044f504826177e3eb438
SHA224 1c23f40d1c94c2337176d7baa3e1d820adf6bd329f84d702f9f4f8e1
SHA256 4418994365912e23b756ec7f14960f1a89230e44e6acb74de055db7c092f8b9c
SHA384 7c717360788affa4fa3ff6681456d2f9153311ae4d712fdce28f2d7ba5c98f13c8e3b409ea710e1f75c9fd11a73cdc6e
SHA512 981e015cb8ade405d59ec9bb723a2e6b876fb40f597b368d7095f6734e64fe09f54cac93a3eb892967fd91f1890982ad1f158c2ae4725af65dab293b6deac9c8

There exist some varieties, notably the NAItube (which will carry a variable weight)[3] and the GTphish (which will trigger specifically as a phishing mail),[4] which are used in the McAfee implementation of SpamAssassin.

The GTUBE is expected to be detected as a substring[5] and is not executable at all, unlike the test for computer viruses developed by EICAR.


  1. ^ "SpamAssassin: The GTUBE". Retrieved 2023-07-13.
  2. ^ "What is a Checksum? | A Definition from". Security. Retrieved 2023-07-13.
  3. ^ "How to generate test messages for Email Gateway anti-spam testing". McAfee. 2019-12-16. Archived from the original on 2020-11-01.
  4. ^ "McAfee Support Community - What is Threat Type: Test". McAfee. 2013-06-07.
  5. ^ "String | Subsequence & Substring". GeeksforGeeks. Retrieved 2023-07-13.