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

[//]: # (werk v2) # HTML Email: Handle SMTP return code 554 as permanent error key | value ---------- | --- compatible | yes version | 2.3.0p15 date | 2024-09-02T12:48:22+00:00 level | 1 class | fix component | notifications edition | cre 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.