Outlook automatically removes certain domains added to safe senders list

Question

Hello. In our organization, we have added some domains to the outlook safe senders list for the purpose of whitelisting them. We fill a notepad file with the domains, which is then used to populate the safe senders list in outlook. This is enforced through GPO. Recently, we had decided to add 2 more domains to this list. After doing so, we noticed that they're being added but then getting removed from the safe senders list after a while. The domains that we're trying to add are internal, but they're managed externally. Can someone explain to me why outlook is removing these domains? Thanks in advance.

Answer 1

Hi @Vasudevan

It appears that Outlook may automatically remove certain domains from the Safe Senders List if they are recognized as intranet domains. Intranet domains are typically considered trusted by default. This is by design.

Intranet domains may be managed externally, but are still considered internal to your organization, which may explain why Outlook might remove such domains from the list of safe senders.

As a result, Outlook may not keep it on the safe senders list, which is primarily used for external domains that users want to whitelist.

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