see your google adwords ad

http://www.google.com/AdPreview

using google like a pro

https://resources.spyfu.com/master-list-every-google-search-operator-40-how-to-use-them/?c=7&g=3

custom email apps and receving emails with user@domain.com via subdomain.domain.com

Remove "via" information from emails not sent through Gmail

Gmail checks whether the messages you send are authenticated.

• If you send messages using a bulk mailing vendor or a third party affiliates, check out Gmail's Bulk Senders Guidelines, including: Publish an SPF record that includes the IPs of the vendor or affiliates which send your messages.
• Sign your messages with a DKIM signature that is associated with your domain.
• Make sure the domain in the "From:" address matches the domain you're using to authenticate your emails.

Emails can be authenticated using SPF or DKIM.

SPF specifies which hosts are allowed to send messages from a given domain by creating an SPF record.

DKIM allows the sender to electronically sign legitimate emails in a way that can be verified by recipients using a public-key.