Microsoft Exchange 5.5 allows a remote attacker to relay email (i.e. spam) using encapsulated SMTP addresses, even if the anti-relaying features are enabled.
https://docs.microsoft.com/en-us/security-updates/securitybulletins/1999/ms99-027
http://www.securityfocus.com/bid/567
http://support.microsoft.com/default.aspx?scid=kb%3B%5BLN%5D%3BQ237927
http://www.ciac.org/ciac/bulletins/j-056.shtml
Source: Mitre, NVD
Published: 1999-08-06
Updated: 2026-06-16
Base Score: 5
Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P
Severity: Medium
EPSS: 0.26099