Hello Mailcow Community, I am currently facing a challenge regarding user restrictions within our organization and I’m hoping someone might be able to offer some guidance. Here’s the scenario: We have three users in our organization: User A, User B, and User C. My goal is to limit the email activities of User B and User C in the following ways: They should be prevented from sending or receiving emails outside of our organization. They should only be able to send and receive emails internally. All users (including User B and User C) should be allowed to log in from outside of our office network without a VPN, using their phones or other devices via third-party clients. However, I want to restrict User B and User C from downloading or uploading attachments when they are outside of the office network. This restriction should be applicable regardless of the device they use. For User A, there should be no such restrictions. They should be allowed to download and upload attachments as needed. I’m aware that a filter can be configured to block incoming and outgoing emails from outside of our organization for specific users. However, I’m struggling to find a way to restrict these users from uploading or downloading attachments. I want to prevent a situation where they could create a draft email with attachments and then download these attachments via their phones or other devices, potentially leading to data theft. Despite these restrictions, I still want User B and User C to be able to view the text part of their emails for notifications, reminders, and calendar events. Any advice on how to achieve these specific restrictions would be greatly appreciated

Restricting User Email Permissions and Attachments Access

Nanak

Hello Mailcow Community,
I am currently facing a challenge regarding user restrictions within our organization and I’m hoping
someone might be able to offer some guidance. Here’s the scenario:
We have three users in our organization: User A, User B, and User C. My goal is to limit the email
activities of User B and User C in the following ways:

They should be prevented from sending or receiving emails outside of our organization. They
should only be able to send and receive emails internally.
All users (including User B and User C) should be allowed to log in from outside of our office
network without a VPN, using their phones or other devices via third-party clients.
However, I want to restrict User B and User C from downloading or uploading attachments when
they are outside of the office network. This restriction should be applicable regardless of the
device they use.

For User A, there should be no such restrictions. They should be allowed to download and upload
attachments as needed.

I’m aware that a filter can be configured to block incoming and outgoing emails from outside of our
organization for specific users. However, I’m struggling to find a way to restrict these users from
uploading or downloading attachments. I want to prevent a situation where they could create a draft
email with attachments and then download these attachments via their phones or other devices,
potentially leading to data theft.
Despite these restrictions, I still want User B and User C to be able to view the text part of their
emails for notifications, reminders, and calendar events.
Any advice on how to achieve these specific restrictions would be greatly appreciated

esackbauer

Its a matter of risk acceptance I guess. They will always be able to bring files outside, as long as they have access to e.g. Dropbox or any other (lesser known or self installed) cloud service from within the office network. At least thats how I would do it 😉

Nanak

So is there anyway to block mail attachment download outside of office network. Firewall or some DLP Solution.
anything.

D4niel

I don’t think it is possible (or at least not easy) to restrict downloads if you want to allow any third-party clients. You can choose freedom or security, but not both at the same time. I’m not sure if Mailcow is even the right product to use here.
I think you might want to look into some kind of mobile device/application management solutions if you want to restrict your users with policies like that. Then they can use one app or software that you can fully configure.

Nanak

So what about a sieve filter that to block incoming and outgoing emails from outside of our
organization for specific users.

bensen

Hi Nanak,

I’m wondering if you could find a way to address N°1 of your questions, since that is exactly what I need to solve too.