More and more users are switching to Google Mail, Hotmail and other free mail services these days. It's a great move... unless you have VirtueMart and your Joomla is set to send your mails through SMTP. You may easily end seeing something like:
Warning: fsockopen() [function.fsockopen]: unable to connect to smtp.gmail.com:25
The mails from other Joomla apps are sent, just the VirtueMart is behaving badly. Weird thing is, that you can see in the main Joomla config the mailer set up properly, and the port to be used is 465, as required for Google Mail, but as you can see the error message indicates that VirtueMart tries to use port 25! The problem is that VirtueMart has a code flaw, when sending mails through SMTP the port 25 is hardcoded, and isn't inherited from main Joomla configuration file.
The fix is relatively easy, but you must get your hands dirty with some PHP code.