Unable to send e-mail. Contact the site administrator if the problem persists (in my localmachine) [closed]
La solution
I guess negative because the post lack of details. Including Drupal Core version (6, 7, 8, 9 ?), name of the modules used to send mails (and it's version), which are required to provide some help/assistance, excpectally if you're not very familliar with Drupal :)
You're saying running the site under local environment, does it provide a mail-sender ? If not, mails can't be sent, then Drupal tell you "Mails can't be send". Nothing more.
If your env is providing a sender, please check if that one is properly configured to send mails (you can found various one-line-commands to check that point)
And then, if both of previous tests were successful, check under Drupal settings if you haven't misspelled a port or a service name (postfix, sendmail ...)