On June 1, 2016, Gmail updated its DMARC policy to prohibit third party email senders from using an @gmail.com address. All such messages sent from a Gmail address outside the Gmail infrastructure (via an email marketing platform) will be rejected by recipients’ inboxes and will not be delivered.
Due to this policy, it will no longer be possible to use a Gmail address to send a marketing campaign or transactional email using any email marketing platform. There are two solutions available for SendinBlue users currently using a Gmail address sender:
Option 1 (Recommended): Update your sender to an email address on your business domain. For example, firstname.lastname@example.org. If you do not have a domain name setup with an email address, you can purchase a domain with email capabilities from most domain providers, such as 1&1 or GoDaddy. Then, you can configure your domain and add new sender(s) in SendinBlue.
Option 2 (Not Recommended): Use a "free" email address that is not provided by Gmail, Yahoo or AOL as your sender. For example, you may still use a Hotmail or Orange address as your sender. However, these ISPs may soon institute a similar policy as Gmail, Yahoo and AOL, which is why we strongly recommend the first solution.
Important Note: If your SendinBlue plan sends email from our shared IP addresses and you continue using a Gmail sender address, we will modify your sender so that your messages are deliverable. Your sender email address will be changed as follows: email@example.com will become firstname.lastname@example.org. If your SendinBlue account sends via a dedicated IP address, we will not alter your sender address. Your emails will continue sending from your Gmail sender, and these messages will be rejected / not delivered by many ISPs and inbox providers.
More Information: Gmail has changed its DMARC policy to ‘p=reject’, effective June 1, 2016. For an email sent via a Gmail address (email@example.com) to be accepted by the ISPs that adhere to the DMARC policy (Gmail, Yahoo and AOL), it must have a "Domain Keys Identified Mail" (DKIM) signature linked to Gmail or a Sender Policy Framework (SPF) linked to Gmail. Otherwise, the email will be rejected and will generate a soft bounce.
This action has been taken by Gmail to effectively combat spam and phishing. Yahoo and AOL adopted similar policies in 2014, and Gmail’s actions could be followed by a number of other ISPs. For this reason, strongly recommend using your own domain in your sender to ensure optimal deliverability for your organization.