There are several custom Spam lists that you can update which are used to check if email is spam or an allowed email.

You can edit the spam lists in the app settings screen. View. Then open the 'Spam' section.
Tap on each list below to view the list and add or remove entries.
You can also add email addresses and other details to these lists in the email details screen. View


Known Senders
This list is a contains email addresses gathered from people who you send email to. The spam rules use this list to do a pre-check of incoming emails to see if the sender is known to you.
The contact list is also used when checking for known senders but contact addresses are not always listed in the known senders list.

Spam Safe List
This list contains a list of addresses and domains that you want to allow. The spam rules will not process emails sent from these addresses for spam. Emails sent from these addresses will always be allowed.
You can add new addresses to this list and you can also add email domains to allow whole companies. For example you could add "@eurosmartz.com" to allow all email addresses from this company.
This list is updated when you swipe to mark spam emails as 'Not Spam'.

Spam Block List
This list contains email addresses that will be blocked and marked as spam. The spam rules will remove all emails with the from address contained in this list.
This list is edited the same as the Spam Safe List.

Domain Suffix Block List
This list blocks emails with from addresses that end with specific text suffixes. For example you could block all emails sent from addresses ending with .shop or .xyz etc.

Sender IP Address Block List
This list blocks the network address of the sender email server. Quite often the same email server can be used to send spam using multiple email addresses. Blocking the IP address will block further emails from the same email server even if the emails have a different from address.
The list contains IPv4 or IPv6 email addresses. You can block network ranges by leaving the last digit off the address. eg. 192.168.44.

Sender Network Name Block List
This list to a wider range of network addresses belonging to the same server host company.
Some email server data centers (ISPs) have a bad reputation for allowing their users to send spam. Good server companies will remove people who send spam from their servers.
You can use this list to block a group of spam email servers which are part of a network group with a bad reputation.
Blocking a network may result in other good email servers so do check the number of emails that you have received from the server network.