No script approval in post actions

I'm sending mails in post block of a declerative pipeline. I'm using currentBuild.rawBuild.getLog(200) to attach Logs to the Mail. Because of missing approval the pipeline didn't send mail and there was no information why. In the log of the build the mail step was missing. The 'In-process Script Approval' page didn't contain a pending signature. It worked after I added the mail step in a stage and approved the signatures.