Email suddenly stopped working

Hi All
Can you help me... my all work has stopped. Email notifications is not working at all.
Neither CONTACT US form, nor i am receiving any emails from customer/orders. News letters are also not sending.

Version- 1.5.1.3

Notice: Error: RCPT TO not accepted from server! in C:\inetpub\vhosts\seeandwear.com\httpdocs\system\library\mail.php on line 316
When i try to send newsletter.

Previously everything was working fine.

Pls help me.

Regards
sainiprabhat@yahoo.co.in

I just answered this here. It's the LAST POST: http://forum.opencart.com/viewtopic.php ... 2&start=20

Thanks for prompt reply , is it possible to use go daddy email SMTP settings if a buy a Email marketing plan from them.
http://www.godaddy.com/business/email-marketing.aspx

but my website is hosted on another server.

Regards
Prabhat

As per my hosting provider their SMTP is Ok because Contact Us form enquiry is going to mail Id provided by them webmail.seeandwear.com but not on google apps mail Id ( that we are using). I have stuck.