Changes

Let's examine this command in detail. First, the '''echo <span style=color:green>-e</span> "<span style=color:blue>subject:Test</span><span style=color:red>\n</span><span style=color:blue>from:[email protected]</span><span style=color:red>\n</span><span style=color:blue>Hello,</span><span style=color:red>\n\n</span><span style=color:blue>JustTesting</span>"''' part:

Let's examine this command in detail. First, the '''echo <span style=color:green>-e</span> "<span style=color:blue>subject:Test</span><span style=color:red>\n</span><span style=color:blue>from:[email protected]</span><span style=color:red>\n</span><span style=color:blue>Hello,</span><span style=color:red>\n\n</span><span style=color:blue>JustTesting</span>"''' part:

'''echo''' - prints the specified arguments to stdout

* '''echo''' - prints the specified arguments to stdout

<span style=color:green>'''-e'''</span> - makes the echo command interpret backslash escapes (</span><span style=color:red>\n</span> in this case)

* <span style=color:green>'''-e'''</span> - makes the echo command interpret backslash escapes (</span><span style=color:red>\n</span> in this case)

<span style=color:red>'''\n'''</span> - the end line symbol, i.e., it indicates that the following text begins in another line. The </span><span style=color:red>\n</span> part itself is not interpreted as part of the text if '''<span style=color:green>-e</span>''' is specified.

* <span style=color:red>'''\n'''</span> - the end line symbol, i.e., it indicates that the following text begins in another line. The </span><span style=color:red>\n</span> part itself is not interpreted as part of the text if '''<span style=color:green>-e</span>''' is specified.

The text highlighted in blue specifies the mail's header information (excluding the recipient's address) and body. In our case it represents this:

The text highlighted in blue specifies the mail's header information (excluding the recipient's address) and body. In our case it represents this: