Need help sorting out an email problem PAID

A client of mine has recently moved to a new server. They are an ecommerce site that sends out many different emails (order confirmations, reset password, order processed etc). Since the move to the new server many clients have reported that they have not received one or more emails sent out by the site that they are used to receive.

Here are the steps I have taken:
1) Set up myself as BCC on all emails - I have been able to confirm time and time again that emails that a client did not receive were sent successfully to me (so the emails are being marked as spam or blocked completey.
2) Tested the content of each email against Spam Assassin and other spam filters - the emails always passed with flying colours
3) Checked their IP against blacklists - passed without issue

I use the php mail() function to send the emails. Maybe using something more advanced could help???

If anyone wants to contact me and offer a hand I am willing to paid for your services if you can fix this problem. I have a budget around $50US paid through paypal.

Thanks,
Chris

 

Ideally the mails should go through. Does it happen with all clients / users or only few?

Try using PHPMailer to send out emails directly via SMTP.

 

Thx Master for the reply. That is one of the thoughts I had. Just short on time right now to implement it!