Not able to send mail from php mail function using MAMP PRO

before few days i have been comfortably sending emails using PHP mail function. but few days back i switched my ISP. and since then i am not able to send any mails. i have setup the postfix configuration of outgoing mail to gmail.com and it gives me the following error in the log file.

   May  6 18:54:05 Ibrahim-Armars-MacBook-Pro postfix/smtp[1449]: connect to aspmx.l.google.com[74.125.53.27]:25: Operation timed out
    May  6 18:54:05 Ibrahim-Armars-MacBook-Pro postfix/smtp[1446]: connect to aspmx.l.google.com[74.125.53.27]:25: Operation timed out
    May  6 18:54:05 Ibrahim-Armars-MacBook-Pro postfix/smtp[1452]: connect to aspmx.l.google.com[74.125.53.27]:25: Operation timed out
    May  6 18:54:05 Ibrahim-Armars-MacBook-Pro postfix/smtp[1455]: connect to mx1.hotmail.com[65.55.92.184]:25: Operation timed out
    May  6 18:54:05 Ibrahim-Armars-MacBook-Pro postfix/smtp[1456]: connect to mx3.hotmail.com[65.55.92.136]:25: Operation timed out
    May  6 18:54:05 Ibrahim-Armars-MacBook-Pro postfix/smtp[1453]: connect to aspmx.l.google.com[74.125.53.27]:25: Operation timed out
    May  6 18:54:05 Ibrahim-Armars-MacBook-Pro postfix/smtp[1454]: connect to aspmx.l.google.com[74.125.53.27]:25: Operation timed out
May  6 18:56:05 Ibrahim-Armars-MacBook-Pro postfix/smtp[1454]: connect to aspmx3.googlemail.com[72.14.213.27]:25: Operation timed out
May  6 18:56:05 Ibrahim-Armars-MacBook-Pro postfix/smtp[1454]: warning: 11C203ECD84: defer service failure
May  6 18:56:05 Ibrahim-Armars-MacBook-Pro postfix/smtp[1454]: 11C203ECD84: to=<azhar@iarmar.com>, relay=none, delay=4504, delays=4353/0.13/150/0, dsn=4.4.1, status=deferred (connect to aspmx3.googlemail.com[72.14.213.27]:25: Operation timed out)
May  6 18:56:05 Ibrahim-Armars-MacBook-Pro postfix/smtp[1454]: connect to aspmx3.googlemail.com[72.14.213.27]:25: Operation timed out
May  6 18:56:05 Ibrahim-Armars-MacBook-Pro postfix/smtp[1454]: warning: 11C203ECD84: defer service failure
May  6 18:56:05 Ibrahim-Armars-MacBook-Pro postfix/smtp[1454]: 11C203ECD84: to=<azhar@iarmar.com>, relay=none, delay=4504, delays=4353/0.13/150/0, dsn=4.4.1, status=deferred (connect to aspmx3.开发者_Go百科googlemail.com[72.14.213.27]:25: Operation timed out)

what could be causing the problem? do you think it is my new ISP? i called there customer care and unfortunately they don't know about this. what would be the possible solution for me to send mail from php , i am using MAMP PRo 1.9.2.

Its very typical that ISP's that provide you with access to internet, will block any connections to port 25 to some other email server besides their own.

You should point your script to use your isp's smtp server to send emails out, not google's as your log files are pointing out.

seems like there is some firewall which is blocking the connection