What is a .LETTER file?
File Extension: .LETTER File Type: Undeliverable Mail File Description: The .LETTER file, often named "dead.letter," is a special type of file that may appear on Unix-based computer systems. This file is typically created when an email fails to send. There are a few reasons why this might happen, such as entering the wrong email address for the recipient or the recipient's email server rejecting the message. Programs to Open This File: The primary program used to handle .LETTER files is Sendmail. Sendmail is a widely used mail transfer agent on Unix systems that manages the sending and receiving of emails.
More Information: If you find a dead.letter file on your system, it indicates that there was an issue with sending an email. You can safely delete this file if you no longer need the information contained in it. However, if email sending issues persist, the dead.letter file might be created again. In such cases, it's important to investigate and resolve the underlying issues with the email sending process to prevent further occurrences.
Note: The dead.letter file is specifically associated with the Unix Sendmail program. It can also be generated when using the PHP mail() function, which might invoke Sendmail in the background to send an email. If you're programming and notice these files, check your mail sending code for errors or misconfigurations.
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