If your emails are not received successfully by your email recipients, a firewall may be blocking your messages. Especially in larger companies, when the same email is sent to multiple people with the same email domain at the same time, these messages may look suspicious.
Email services like Gmail, Outlook.com and Yahoo or company domain addresses (eg. firstname.lastname@example.org) block email to protect you from unwanted or malicious email such as phishing, scams and spam. They may mistake your emails for one of these malicious emails.
Adding legitimate senders (whitelisting) to your email service may improve your messaging deliverability. The method to whitelist email domains in will vary based upon the service used. Your service may ask you to:
- add a contact as a safe sender
- adding as a contact into your contact book
- create a filter
Refer to your email service's Help Center for updated instructions on whitelisting. See below for common methods to whitelist with popular email services. There are also great sites that document this process for you like this one: http://www.whatcounts.com/how-to-whitelist-emails/
- Open a message from the desired sender.
- Click the arrow next to reply on the top right.
- Click Add sender to contact list.
Mark messages as ‘Not spam’
- Select spam folder.
- Select email(s) mistakenly marked as spam.
- Click More and then Not spam.
Create a filter for the address
- Click the cog icon in the top-right corner, and then Settings
- Click on Filters and Blocked Addresses
- Select Create a new filter
- Enter the domain of the email you want to whitelist in the From field
- Click Create filter with this search
- In the box headed When a message arrives that matches this search select Never send it to spam
- Click the Create filter button
- Open a message from the desired sender
- Go to Message in the top tool bar
- Click Add Sender to Address Book from the drop-down menu