shmem has given you and answer using look around assertions but if you were to do this using regex captures you have to disambiguate the capture using braces. Your code is trying to replace with the variable $1something which, unsurprisingly, doesn't do what you want. Try something like

use strict;
use warnings;

$_ = q{aaa@z.com bbb@z.com ccc@z.com};
print qq{$_\n};

s{([^@]+@)[^.]+}{${1}something}g;
print qq{$_\n};

[download]

which produces

aaa@z.com bbb@z.com ccc@z.com
aaa@something.com bbb@something.com ccc@something.com

[download]

Cheers,

JohnGG

Update: shmem has pointed out that I'm completely wide of the mark here and that $1 and friends are never ambiguous.

In reply to Re: replacing email id using regex by johngg
in thread replacing email id using regex by Anonymous Monk

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