No 3 should already work based on
http://www.mantisbt.org/wiki/doku.php/mantisbt:plugins:emailreporting#mail_add_bugnotes -> YES
http://www.mantisbt.org/wiki/doku.php/mantisbt:plugins:emailreporting#mail_subject_id_regex -> You choose
http://www.mantisbt.org/wiki/doku.php/mantisbt:plugins:emailreporting#mail_use_message_id -> YES

No 2 requires you to set up MantisBT notification emails
http:// [your host]/[your MantisBT folder]/manage_config_email_page.php
Customers need to have an account connected to their email address and that account needs to be the reporting user of the issue
http://www.mantisbt.org/wiki/doku.php/mantisbt:plugins:emailreporting#mail_use_reporter -> NO
http://www.mantisbt.org/wiki/doku.php/mantisbt:plugins:emailreporting#mail_auto_signup -> YES
Users need to get notifications about their own actions
http://www.mantisbt.org/wiki/doku.php/mantisbt:plugins:emailreporting#mail_email_receive_own -> YES

That should do it...

Hii,
Thanks for the reply.
Here we have one more doubt in mantisBT auto respond.
1) As per trail mail we make a settings up in MantisBT notification emails & manage_config_email_page.php and
then able to send auto respond to that customer.
2) But after some time unfortunately auto respond is stopped.
3)Now, what you need to do is to constantly respond to the customer.?

Thanks,
Giridhar.

Then you need to find out why it stops. Because i don't have access to your environment
If there is an error that is reported by MantisBT or EmailReporting please post it here so that we can investigate further

Hii,
1)We have configured Email_reporting plugin/MantisBT should auto respond to that customer along with his ticket ID.
2)But in this case the auto respond notifications are continuously received in mail box.
3) And the same emails are received repeatedly.
4) Please suggest in configuring of above points in MantisBT.
Thanks.

Like i said, somewhere an error is encountered and you need to find out what it is.
The best way to do this is to run the bug_report_mail.php script manually and see what errors are returned.
You might need to add this to your MantisBT config_inc.php

# --- detailed error messages -----
$g_show_detailed_errors = ON;

# --- error display ---
$g_display_errors = array(
    E_WARNING => 'halt',
    E_NOTICE => 'halt',
    E_USER_ERROR => 'halt',
    E_USER_WARNING => 'halt',
    E_USER_NOTICE => 'halt'
);

Hi,
Here we have one more doubt in mantisBT email repporting,
1) We are sending email to user id which is add in particular one project.
2) but still not receive mail to that user.
3) How to configure mantis to send email to the particular project user in mantisbt.
Thanks.

EmailReporting should behave more or less the same as MantisBT. So if a certain MantisBT action triggers a notification, the same should happen for EmailReporting

1. First check whether or not emails are actually sent: /mantisbt/admin/email_queue.php
2. Check the notification settings for global and project to see if thats correct: /mantisbt/manage_config_email_page.php
3. Have you set up the settings as described here: 0026431:0063189

Good evening, downloaded, installed, and configured. The only problem is that tickets are not being opened following the sending of the email that is sent to an email address configured for email reporting; I have set up the cron in the provider's system. What am I doing wrong? Is there anyone who can give me some advice? Thank you.

Normally i would ask to continue this on the forums (mantisbt.org/forums/viewforum.php?f=13). But since they currently have issues.
On the EmailReporting configuration page you can run the job manually. If it works there but not automatically then there is an issue with the cronjob.