Hi @nandayellow ,
There are a few issues here. First you have exceeded the 255 character limit. Second, you also have a bunch of HTML tags from the email body.
Please refer to the below flow. I have purposely split up the steps into separate actions to make it easier to understand.
1. Convert the HTML body to text
2. Use concat() to join the from address and email body text
concat(triggerOutputs()?['body/from'],outputs('Html_to_text')?['body'])
3. Check the output from step 2 to see if it is 255 characters or more, if so, only get the first 255 characters, otherwise, just pass the entire string
if(lessOrEquals(length(outputs('Compose')),255),outputs('Compose'),substring(outputs('Compose'),0,255))
Please refer to this link for the details of the above formula.

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