Shamim's Plugins

We cannot send email from an email address which we do not own. You do not own your user email address, so you can not send email from that email address. We can try but most of the cases it will fail.

add following code in your theme’s (child theme’s if using) functions.php

add_filter( 'fep_get_user_groups', function( $user_groups, $user_id ){
    $groups = fep_get_option('gm_groups', array());
    if( $groups && is_array( $groups) ){
        foreach ( $groups as $group ) {
            $user_groups[ $group['slug'] ] = $group['name'];
        }
    }
    return $user_groups;
}, 10, 2);

Please follow https://www.shamimsplugins.com/docs/front-end-pm-pro/getting-started-2/translate/

Your other questions need some code. But i am outside. I will be back after 1 week. Then i will give you some code to achieve those changes.

If you show photos then there is a easy way to show the other user photo only
Add following code in your theme’s (child theme you are using one) functions.php

add_filter( 'fep_remove_own_avatar_from_messagebox', '__return_true' );

Or to show names of other user you have to use fep_message_table_column_content_author action hook. It needs some custom code. You need participants name then remove own name from them.

You can use some regex to do that but it does not always works. Users can change their mobile no or email a little to bypass this.

Did you changed your theme to tweenty* and deactivate all other plugins including all custom plugins except this and test?

If above steps do not solve your issue please give me access to your test website so that i can test. Please use https://www.shamimsplugins.com/sensitive-information/ for sending credential.

You can add -----Reply Above This Line----- on top of email content in Front End PM PRO > Settings > Emails. Then add following code in your child theme’s functions.php

add_filter( 'fep_filter_message_before_send', function( $message ) {
	$message['message_content'] = strstr( $message['message_content'], '-----Reply Above This Line-----', true ) ?: $message['message_content'];
	return $message;
});

You want a admin field (like user blacklist in security tab) where you can add message keys and users will not be able to reply those emails, right? Can users reply from website?