Currently EmailReporting does not support this.
This should be possible with a new feature that is in development... but it has been for years now and its unclear when it will be finished

For the moment you've got 3 ways to fix this

1. Modify EmailReporting yourself as required
2. Use POP3 and create multiple mailboxes and let EmailReporting process each one. You only need to worry about new issues. Notes will always be properly processed no matter what email address they were received on
3. Use IMAP with sub folders and one single mailbox. EmailReporting can create a project folder structure in the mailbox and process each email in it to the proper project in MantisBT. You could make automatic rules that move incoming emails to the folders based on the email address they were received on (bugs_*@example.com)

I believe solution 3 should work best at the moment but it depends on your mail server whether or not that is possible

Hello

0. This is a feature request ;-)
1. Too busy at this time;
2. This is what I want to avoid as it requires server & EmailReporting configuration for each mailbox;
3. The email service does not allow this. The only way to achieve this is to have another email client running that would apply the rules on the inbox.

I suggest to keep the feature request open until there is enough interest for it.

We've added the ability for the rule system to update the project: https://github.com/mantisbt-plugins/EmailReporting/commit/5718529a809e34c35974764e9ab2f7e6399e589f
The rule system can also check the from and to email addresses

This will be released in 0.14.1 or 0.15.0