1- If you have not receive email yet then Please create a domain email like

[email protected] and then come to

WordPress Dashboard --> Settings --> General --> Here you will see Email Address Option .
Please change this to domain name email.

Then come to WordPress Dashboard --> Classiera Options --> Contact Page --> Also change email from here.

Then post new ads, I hope you will receive email.

2- First you need to apply point first if that will not work then install this plugin.

https://wordpress.org/plugins/wp-mail-smtp/

Configure this plugin. I am sure you will receive email.

3- If still no email then you need to contact with your hosting support. Because some hosting server blocking wp-mail function.

Thanks