Signup with email authentication, only 30% are activated? - php

Question

I am using php and mysql. And my site is in flash (full flash site)
I have a website which let users to sign up. The signup process including sending "activation email", click link to activate account.
The first two weeks was fine. Out of around 2000 users, 1800 users are activated. After that, the activated users drop drastically, to about 30%. Example: 1000 users signup, only 300 were activated.
At first, I found the problem is because the email could not be reach to ymail, msn and gmail users. (Most of my subscribers are Ymail (yahoo), hotmail/msn(live) and gmail (gmail)). I tried signup using ymail and hotmail, but i didnt get any activation email. I contacted yahoo and msn, eventually my email can go through now.
However, my signup statistic still showing, the activated users are only about 30%, which very confuse me. I contact my hosting company, ask them the whitelist my IP. And they did it.
I need your advice/help on following questions:
How to check where the problem lies? Is the email not delivered? User receive email but didnt click the activation link?
I am using php mail funstion. and this is my headers:
$headers = 'MIME-Version: 1.0' . "\r\n";
$headers .= 'Content-type: text/html; charset=UTF-8' . "\r\n";
$headers .= 'From: Admin <\admin#domain.com>' . "\r\n";
$headers .= 'Return-Receipt-To: Bounce <\bounce#domain.com>' . "\r\n";
$headers .= 'Reply-To: Admin <\admin#domain.com>' . "\r\n";
$return_path = "\bounce#domain.com\";
(I hide my domain name, and i add backslashes within emails, cuz if not, the email wont show here, weird)
Is there anything wrong with the headers?
What can I do to improve my registration/signup activation process?

Answer 1

You should pass your return path as "-f" parameter for mail() function:
mail(
$this->recipient,
$subj,
$this->body,
$this->compose_headers(),
'-f ' . Options::obj()->mail->return_path);
Also, for the best results, if the sending server has a public domain name example.com, the return path should be something#example.com.
Anyway, you should definitely check the logs (/var/log/mail*) to know exactly what's going on.

Answer 2

Try using gmail as your smtp server istead of mail server like sendmail from a domain. Using gmail smtp would kinda ensure that your mails are sent on best effort surity. Also Gmail would not be treated as spam unless email id is marked as spam (so try using a one which is safe). To improve singup->activation through put your best bet is to ensure that email is reaching user's inbox.
For safety net you can have a feature in which you allow user to resend the activation link if the first one failed for some reason.
If you are uncomfortable using gmail as smtp, you can sign up ur domain with google apps (but that might require changes in business needs) and you can have admin#domain.com kind of email and still use efficient gmail smtp servers.
There are many libraries out there like phpMAiler which allows to use external smtp servers. Note all data through gmail servers go via SSL or TSL.

Answer 3

Do you have access to the log files of the email server sending out the registration emails? Any bounced emails normally go back to the sending server. By monitoring the log files you can check and see what number of emails (if any) are still getting bounced back.
What kind of access do users have to your web site without an activated email address? Are any features disabled? Are there any incentives to activate or use a real email address?

Answer 4

Your example doesn't show a Date header which is a required field. In my experience some mail handlers reject emails that don't have one (and some just add one with the current date.) If your actual code doesn't have one then try adding one and seeing if it makes a difference.
Search for RFC2822 for information on what is required,