Spam Filter Whitelist: Permanently Allow Trusted Senders

Spam Filter Whitelist: Permanently Allow Trusted Senders

If important emails from business partners, customers, suppliers or newsletters accidentally end up in spam, you can add these senders to the so-called Whitelist. In SpamExperts, this function is called the Sender Allow List.

Emails from senders on this list are treated as trusted by the spam filter and are usually delivered directly. This helps ensure that legitimate messages are not incorrectly blocked or marked as spam.

When should I add a sender to the whitelist?

Whitelisting is useful when you know that a specific sender is trustworthy and their emails should be delivered reliably. Typical examples include:

• business partners, customers or suppliers
• internal email addresses of your company
• newsletters you have intentionally subscribed to
• accounting, shop or CRM systems
• contact forms or automated notifications

Especially in a business environment, a properly maintained allow list is important to prevent relevant communication from being missed.

How to add a sender to the Allow List

1. Log in to the spam filter dashboard.
2. Navigate to “Incoming – Sender Allow List”.
3. Click “Add sender”.
4. Enter the desired email address or domain.
5. Save the change.

Allow an individual email address or an entire domain?

You can either add an exact email address or an entire domain to the whitelist. Which option makes sense depends on how broad the permission should be.

Best practices for safe whitelisting

• Prefer allowing individual email addresses instead of entire domains.
• Check whether the sender is truly trustworthy before whitelisting.
• Avoid allow-listing large public email providers.
• Review your Allow List regularly and remove entries that are no longer needed.
• Do not use the whitelist as a replacement for SPF, DKIM and DMARC.

What happens after adding a sender to the whitelist?

After a sender has been added to the Allow List, the spam filter treats future messages from this sender as trusted. In many cases, these emails are delivered directly and are no longer moved to quarantine.

Please note: Emails that have already been blocked or placed in quarantine are not automatically delivered afterwards. If required, they must be released manually from the quarantine.

Whitelist, block list and quarantine: What is the difference?

• Whitelist / Sender Allow List: Allows trusted senders.
• Blacklist / Sender Block List: Blocks unwanted senders.
• Quarantine: Contains suspicious emails held back by the spam filter.

The whitelist is therefore the right tool if you want to make sure that certain emails are not incorrectly treated as spam.

Frequently asked questions about the whitelist

Can I allow an entire domain?

Yes. With an entry such as *@partner-company.ch, you allow all email addresses from that domain. Use this option only for domains you fully trust.

Should I whitelist Gmail, Outlook or other large providers?

No, this is strongly discouraged. Public email providers are also used by spammers. A global allow entry for such domains can significantly reduce the effectiveness of the spam filter.

Are already blocked emails delivered automatically?

No. The whitelist generally applies to future emails. Messages that are already in quarantine must be checked and released manually if needed.

What can I do if important emails still do not arrive?

First check the quarantine and verify that the sender has been entered correctly. Pay close attention to typos in the email address or domain. If the issue continues, the CURIAWEB support team will be happy to assist you.

Learn more about email security and spam filtering »