[2.2.0] Checkmk Werk 17166 created: HTML Email: Handle SMTP return code 554 as permanent error

Title: HTML Email: Handle SMTP return code 554 as permanent error Class: fix Compatible: compat Component: notifications Date: 1725281302 Edition: cre Level: 1 Version: 2.2.0p33 If you used "Enable synchronous delivery via SMTP" the return code 554 was not handled as a permanent error, leading to multiple delivery attempts. This return code is now handled as permanent error.