Email not always sent after PayPal purchase

Hello, we've been using TurboActivate for over a year now and it's working well, except for one thing. Many of our users report that they don't get the activation email after purchasing via PayPal. I'd say this happens 25-30% of the time. We can't figure out why it works sometimes and not other times. The code we are using is directly from your PayPal example code.

My theory is that somehow it is getting caught in spam filters. If that's the reason, can you please advise how we can improve the odds that the email will not get caught? If that's not the reason, can you please let me know what else we can do? This is a serious issue, since we do not always have someone available to re-send keys, especially on the weekends, and our users get frustrated because they have to wait for something that they were told would be immediate.

Thanks in advance for your help.

If the emails are actually leaving your servers successfully (check your logs to make sure no obvious error is happening), then yes, you've got a spam-false-positive problem.

The solution is to make your email look less spammy, to use proper email signing (domain keys, spf, dkim, etc.) and to make sure your reverse DNS is set. This tool will find some of the more obvious problems for your.

Or just outsource the whole email sending business to a company that does this for a living:

Ok, that's helpful. Thanks!