You’ve made a pretty good job of revealing lots of sensitive information in one post to a public forum.
You’ve disclosed your Blynk template ID, Auth token, WiFi SSID and password and your email address!
As the error message says, the problem is with this line of code…
If you read the documentation it tells you that Blynk.email() is a legacy feature, and for IoT you need to…
Replace Blynk.notify(), Blynk.email(), Blynk.tweet(), Blynk.sms() with Blynk.logEvent(). Read this guide on how to set up Events with notifications.
You’re already using Blynk.logEvent(), so you actually need to delete the problematic line of code and change the way that your event and it’s notification tab are configured.
However, you have a flaw in the logic of your code which - under a prolonged period of the smoke detector reading being above your threshold - will result in you exceeding the 100 maximum logEvents per 24 hour period.
You should use a flag variable to avoid that happening. See this for more info…
Pete.