No Email notification only for one of services of a host

Hello Everyone,
i have a host in Icinga2 with 5 Services. Mail notification works for the host itself and only 4 of its services. by one of them it sends no notification. I looked into the /var/log/icinga2/icinga2.log and it says that the notification for this service on this host is logged. but it never sends it.
What can be the Problem?
Wheni looked into this servise on icingawe2 , the notification option is enabled for this Service.

  • Icinga Web 2 version 2.11
  • Icinga 2 version used (icinga2 --version) : 2.14
  • PHP version used (php --version): 7.4
  • Server operating system and version: RHEL

I am very thankful for your answers and time.

Was the message to long for the mail script to send it?

if you mean the message in icinga2.log, there it is:

[2023-11-09 12:35:47 +0100] information/Checkable: Checkable ‘service Check’ has 1 notification(s). Checking filters for type ‘Custom’, sends will be logged.
[2023-11-09 12:35:47 +0100] information/HttpServerConnection: Request: POST /v1/actions/send-custom-notification (from []:xx), user: icingaweb2, agent: , status: OK).
[2023-11-09 12:35:47 +0100] information/HttpServerConnection: HTTP client disconnected (from []:xx)
[2023-11-09 12:35:49 +0100] information/ApiListener: New client connection from []:xx (no client certificate)

No, I mean the message of the check plugin. If it produces a wall of text, the mail can get to long and can’t be send.

But a custom message will send.

no the output by Critical status is not that long. maybe 2 or 3 lines.even when i send notification by myself from icingaweb2 and only write for example “test” in it it wont be sended. it is only logged.

I have the very same service on another Host and on other host it send notification and evrything is ok.
i dont understand why is that so.