Config file for Mail App and Nextcloud installed with Snap

Have installed Nextcloud via snap. Having issues with the Mail app. Not able to send out mails but able to receiving mails. have read some posts where it says to try changing the ā€˜app.mail.verify-tls-peerā€™ to false. But not able to find the path. any info regarding this will be of great help. Environment is Ubuntu 20.04

Thanks