Outlook Is Not Importing The Entire Safe Senders List From GPO

Hi @Anonymous ,

What's the mailbox server that you are working with(Exchange server or others)? And could you add those safe senders to list manually in Outlook client now?

If you also couldn't add them manually, the issue may be related to your server limit instead of GPO settings or Outlook.

As I know, in terms of Exchange, Microsoft Exchange limits the space that's allotted to your various Junk E-mail lists. By default, this limit is 510 kilobytes (KB). For more information, please refer to this document : Outlook error indicates that you are over the Junk E-mail list limit.

If that's not your case, considering corrupted list file may also cause it, in order to avoid the interference of current text file, it's recommended to create a new file and re-configure it to your Outlook client to check if the issue has any difference after that.

Update:

According to my tests, I have tried to created a .txt file with 5200 items and deploy it through GPO, then I found it could add all items normally in my Outlook like below:

Here are my detailed steps to configure it:

• create a txt file with 5200 addresses
• Deploy GPO(Enable "Trigger to apply junk email list settings" and set "Specify path to Safe Sender list")

• check the register editor to confirm the configuration

If your steps are same with mine, in order to further confirm if your issue is related to your mailbox or your GPO, it's recommended to create a new Outlook profile and add another accout in it(preferably a mailbox without any list) to check if all items could be added normally there(Control Panel>Mail>show profiles>Add>Add your account). If the issue could be reproduced on this mailbox, I think the issue may be related to your GPO, please first ensure that you are working with the latest version of Administrative Template files.

If your issue has any update, please feel free to post back.

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Hi Jade,

Thank you for taking the time to replicate this in your lab! I have verified the policy settings are accurate. I also made a new file in the same location and changed the policy to point to that file. No change. I then copied the file to a local location on both test computers (c:\users\USERNAME\desktop\safesenders2.txt).

The registry shows the correct location as specified in the GPO.

In all 3 instances, I encounter the same issue. Outlook only imports part of the addresses on the list. The address list is made correctly. All addresses are either user@keyman .com or @keyman .com.

I'm using the latest ADMX templates. I installed the latest ones just 2 weeks ago.

EDIT:
I logged in with another windows account and fresh outlook profile. Same issue. It appears to only import about 550 lines of the list.

EDIT 2:
I figured it out. There are two issues. 1) one of the email addresses had an invalid special character inside of it. 2) The email addresses were not listed alphabetically. Resolving those two issues fixed the problem. Thank you for your help.

Hello,

In Outlook.com and Office 365, the limit is 500 on the blocked list and 1024 on the safe lists.

In Outlook and older versions of Exchange, the limit is approximately 1000 total. This is because the total size of all lists combined cannot exceed 510KB. Once the 510KB limit is reached, Outlook alerts you and additional addresses aren't saved until you remove some from the list.

For example, if you have 800 addresses on the safe list, you can only block approximately 200 addresses. If the addresses are long, your list will hold fewer addresses; if they're short, you'll be able to have more.

Microsoft imposed the limit to improve performance, as the lists are stored as a hidden property in the Inbox and duplicated to the local registry. Each time the users synchronize with the Exchange mailbox store, the lists are downloaded.

The limit can be adjusted on Exchange Server 2007 or 2010, by adding a new registry key value to the following registry key. This option is not supported on Exchange server 2013 and newer, including Office 365.

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\ParametersSystem\
DWORD: Type Max Extended Rule Size
Value Data: maximum size (in bytes) that you want to allow
Importing a list of blocked addresses from an older version of Outlook is not recommended, in part because these lists often are larger than 512K and Outlook crashes when trying to import them, but also because spammers change addresses so often that lists are outdated within a few months.

If Outlook's Junk email filter doesn't offer enough options, misses too much spam, or you need better Safe and Blocked lists, try one of the many excellent third party anti-spam filters available.

--Do not forget to vote if helpful, or mark as answer if it resolved your query --

Best regards,

Luis P