"Safelisting" (also known as "Whitelisting") is a term used in the Web industry to add certain e-mail addresses to mailbox contacts.
This process is important because it will greatly increase the chances that all emails sent from a particular mailbox will reach you, thus avoiding unpleasant situations in which you omit an important message.
In the following, we will go through the steps of adding an e-mail in the address book, on different popular platforms:
Sign in to your Gmail account and select the email you want to add to your contacts.
Move your cursor over the email box and then access the sign "+"
Safelisting for Yahoo mails follows a similar process to Gmail.
The email containing the targeted address will be accessed, the cursor will be moved over the e-mail address, and then you will click Add to Contacts
For Outlook, you will need to go to the settings section at the top of the window first, then go to "View all Outlook settings"
In the open window will go to Mail -> Junk email, then in the section "Safe senders and domains" you click "+ Add" and enter the desired mailbox
We access Address Book from the top menu bar
We make sure that the section Personal Address Book on the right is selected, after that we click on New Contact
The contact details will be filled in the open window, after which the process will be completed with the confirmation button Ok
We will access the e-mail, then click on the e-mail box and lastly Add to Address Book
Similar to the method used for Yahoo and Gmail, adding the contact is done by accessing the email box from which the email was received, after we finish the procedure by clicking Add to Address Book
However, there may be situations where emails won't reach you even if the address has been added to your address book. This can usually be due to the low reputation of the mailbox, or IP for the server from which the message was sent is in a blacklist.
You can find more information about rebuilding the reputation of a Gmail mailbox and the impact of blacklists in the articles:
For gMail, on your phone, hit the 3 dots at top right corner, click "Move to" then "Primary."
Apple mail users: Tap on our email address at the top of this email (next to "From:" on mobile) and click “Add to VIPs”