Un-Send! is an episode of the ALVINNN!!! and The Chipmunks series.
Alvin encourages Simon to write an e-mail to vent about his demanding professor, and the e-mail accidentally gets sent.
Kevin and Simon anguish over their computer science work for Dr. Haywood; Simon's reassured he's getting close while Kevin reaches his daily limit and bursts out of the classroom. At the Seville House, Simon explains to Alvin that the class is too much to handle so Alvin gives him an opportunity to vent out his frustration. Simon finishes to learn Alvin typed his vent as an email, and, in an attempt to delete the message, Simon accidentally hits send when Theodore opens their bedroom door. Simon retrieves his laptop and finds Alvin also embellished the message. Hesitant, his younger brothers convince him to hack into his professor's email only to be stopped by "Keep Out," a security system built by Dr. Haywood. Simon reveals that they must be at his professor's computer to delete the email but, outside the school, find "Keep Out" protecting it as well. Following a moment of panic, Simon disables the cameras and tricks the retinal scanner using his phone and Alvin's eye. Inside they bypass lasers for Theodore discovered a beat in their movement and danced through them. Finally to the classroom computer Theodore guesses the password is "password," which it was, shortly before the professor enters the room. Amused by the email, he tells the boys a story about himself doing the same thing. To help Simon in the future, he agrees to check in with Simon's other teachers before Alvin learns the professor likes to play one of his games.
- "Never Meant to Hurt You" 
- A sneak peek clip was released on Nick.com.
- The clip of Theodore dancing between the lasers is included in the second series opening theme, first seen at the start of season three.
- When this episode premiered in the US, it aired with a rerun of Secret Admirer.