You need a trailing . on the source directory path:

SOURCE="[email protected]:/var/www/vhosts/namesiteA.com/." 

With the new SFTP-based protocol for scp you need a trailing . on the source directory path:

SOURCE="[email protected]:/var/www/vhosts/namesiteA.com/." 

Unfortunately if you're using a legacy version of scp that uses the old scp protocol, and it's new enough to be updated with a fix for CVE-2018-20685, the trailing dot will break the copy. See scp: error: unexpected filename