Could not instantiate mail function

I Installed post_notification as well as subscribe2 plugins,both are not sending EMAILS (notification); I have contact email page too; that also shows Error (Error sending message!)

but from all blogs i get comment notification as well as new post notification from bbpress. that means mail function is working wp_mail();

Anyone faced this problem….?

Here is Post_notification plugin error
————-
The mail has not been sent!
PHP-Mailer – Dump:
object(PHPMailer)#277 (53) {
[“Priority”]=>
int(3)
[“CharSet”]=>
string(5) “UTF-8”
[“ContentType”]=>
string(10) “text/plain”
[“Encoding”]=>
string(4) “8bit”
[“ErrorInfo”]=>
string(36) “Could not instantiate mail function.”

…..

[“provide_address”]=>
string(54) “You must provide at least one recipient email address.”
[“mailer_not_supported”]=>
string(25) ” mailer is not supported.”
[“execute”]=>
string(19) “Could not execute: “
[“instantiate”]=>
string(36) “Could not instantiate mail function.”
[“authenticate”]=>
string(35) “SMTP Error: Could not authenticate.”
[“from_failed”]=>
string(35) “The following From address failed: “
[“recipients_failed”]=>
string(45) “SMTP Error: The following recipients failed: “
[“data_not_accepted”]=>
string(30) “SMTP Error: Data not accepted.”
[“connect_host”]=>
string(43) “SMTP Error: Could not connect to SMTP host.”
[“file_access”]=>
string(23) “Could not access file: “
[“file_open”]=>
string(33) “File Error: Could not open file: “
[“encoding”]=>
string(18) “Unknown encoding: “
[“signing”]=>
string(15) “Signing Error: “
[“smtp_error”]=>
string(19) “SMTP server error: “
[“empty_message”]=>
string(18) “Message body empty”
[“invalid_address”]=>
string(15) “Invalid address”
[“variable_set”]=>
string(30) “Cannot set or reset variable: ”