You don't show us a script, but this is what use strict; does - it forces you to predeclare all the variable names you intend to use. This is a good thing because it finds typos like the following:

use strict;

my $variable_with_a_very_long_name = 1;
print "The value is >>$varaible_with_a_very_long_name<<";
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As your script seems to work with use strict; commented out, likely your script contains no typos and all you need is to predeclare your global variables:

# for global variables:
use vars qw(@users $account);
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If a variable isn't used in global scope, you want to declare it lexically within the block it is used in via the my keyword:

for $user (@users) {
    $message = "Hello $user!";
    ...
};

# should become

for my $user (@users) {
    my $message = "Hello $user!";
};
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warnings are somewhat less vexating, but produces some notification run-time messages when a weird condition arises. For example, when you print or otherwise "use" an undef variable, it warns you that this is happening, and that it's probably something that you should avoid.

For a somewhat frustrated dissertation about the whole issue, you can read On Commenting Out 'use strict;'.

Some Global variables require explicit package name

that said - please copy & paste the exact error message so people can help you better.

How to solve your problem:

• Read the list of errors emitted by Perl
• Locate the variables which are listed. Perl helps here, as it gives line numbers.
• Determine the minimum scope required for each variable. As an example, the scope for a loop index need not be more than the loop where it's used, and most variables in functions should have their scope limited to the function in which they're used.
• Declare each variable with my, our, or local, as appropriate.

could you post your code? so that it is for us to explain the things better.