How to avoid sending your Salesforce emails straight to spam?

By using Salesforce’s Email Relay functionality. Email relay automatically routes Salesforce-generated emails through your company’s mail service. An email relay uses an email server to send emails that originated somewhere else.Email Relay Setup: 1. For being able to use ‘Email Relay Action’ in Salesforce, the System Administrator has to perform the following steps: Create a Support case with Salesforce Customer support to enable Email Relay in your organization. In the case details, provide the following information:
The organization ID for which you want the feature enabled.
The text: ‘Allow Email Relay Enablement.’
Note: System Administrator needs to perform this step only once. To check if the feature is enabled in your org or not, search for “Email Relay Activation” in setup. If you can see it, it is already enabled.
From setup, enter Email Relays in the Quick Find box and select Email Relays.
Select Create Email Relays. The following setting needs to be configured:
Enable SMTP Auth
Host
Password
Port
TLS Setting
Username
Save the page and set up the Email domain Filter by searching Email Domain Filters in the Quick Find box in the setup.
Select “Create Email Domain Filters”. Configure the following settings:
Sender Domain
Recipient Domain
Email Relay
Housekeeping steps for successfully setting up Email Relay
Setting correct Deliverability settings and email relay so as to prevent modification of envelope From address of the email sent and the return-path. Any change in the email headers affects email delivery to the email server. The following 2 settings in the email deliverability must be disabled:
a) Turn OFF “Activate Bounce Management” b) Turn OFF “Enable compliance with standard email security mechanisms”
How to Secure Email Relay:
Have your email relay whitelist only the IPs you want to relay mail for (ours and any others)
Only relay mail that is sent using your mail domain
Enforce TLS (optionally set it to TLS required or required and verify the hostname on the certificate)
Have your relay verify the hostname on our certificate
Look for a header – X-SFDC-LK and ensure that it has your Org ID in it. Only relay mail from salesforce if it has the proper Org ID
Use DKIM signing in salesforce and only relay mail if the DKIM signature passes
Advantages of Email Relay
Apply existing content filters to scan messages for data and content not approved for company email.
Route all email through your own email servers to avoid the appearance of ’email spoofing’ forgeries.
Store copies of all email as required by government regulations in various industries.
Run outbound email through antivirus software before sending it to customers.
Automatically add data, such as company-wide disclaimers, at the bottom of email messages.