Mail whitelisting based on recipient

Discussion in 'General' started by NueX, Dec 5, 2015.

  1. NueX

    NueX New Member

    Hello everybody,

    First of all, thank you very much for this great tool, ISPConfig! My server is up and running, everything fine. But I have a question: I could neither find the answer in the manual, nor here in the forum:

    I want to be able to "invent" valid mail-adresses as soon as I have to sign up to some online service, each with individual adresses. That's how I do it:
    - xyz.mydomain.com (a subdomain dedicated for all "invented" mail adresses)
    - *(AT)xyz.mydomain.com (catchall to receive all mails on this domain)
    - *(AT)xyz.mydomain.com (blacklist with low priority to sort out unwanted incoming mails)
    - *_xyz(AT)xyz.mydomain.com (whitelist with high priority to enable all incoming mails of the shape *_xyz(AT)xyz.mydomain.com, e.g. invent1_xyz(AT)xyz.mydomain.com, invent2_xyz(AT)xyz.mydomain.com, ...)

    The advantage of this setup: individual login-mail-adresses for all website I have to sign up, based on the format *_xyz(AT)xyz.mydomain.com. On the other hand, should spammers start to spam me on *(AT)xyz.mydomain.com, all mails not following my "secret" format will be rejected. I usually chose servicename_xyz(AT)xyz.mydomain.com to be able to identify the origin of spam which already helped me several times (once with a dropbox user data leak, once with an online shop that got hacked, both causing a spam wave).

    Is it possible to realize this with ISPConfig? I just found white and black lists based on sender adresses, which does not help in this case. Help or comments very welcome!

    P.S.: Sorry, the forum forced me to write the adresses in this way...
     
    Last edited: Dec 6, 2015
  2. sjau

    sjau Local Meanie Moderator

    That should be possible.

    However I prefer creating aliases. E.g. my real email setup in ISPC is:
    [email protected]

    On website xyz I need to provide an email. So I'll create the alias [email protected] which points to [email protected].

    I have on my notebook a test-apache server running and wrote myself a small script to create email address easily.

    In the past spammers tried to use all different kind of ...@domain.tld and so I've abandoned the wildcard approach as you may want to do and went for actual aliases. If an alias doesn't exist, then postfix will refuse to accept the email.
     
  3. NueX

    NueX New Member

    Thank you very much for your reply. Do you have a hint, how to realize white/black lists based on recipient from the ISPConfig control panel?

    I see your approach and agree, that it works well and even gives you an overview over existing addresses. However, my approach would be a bit different as the server does not need to know the exact addresses, rather just the general structure. As spam protection, the filter against raw *(AT)xyz.mydomain.com should be enough. Automated spam is not yet smart enough to identify the required whitelisted structure *_xyz(AT)xyz.mydomain.com.

    For example: I do not always have access to my personal laptop or the server but still want to be able to leave a "fresh" mail address somewhere. This is, where my approach comes in. Came up with this when I had to abandon the general catchall approach.
     
  4. sjau

    sjau Local Meanie Moderator

    Try:

    1. Log into ISPC
    2. Go to "Email" tab
    3. Add new mail domain: xyz.domain.tld (don't forget to add dns entries as well)
    4. Click on "Email Alias"
    5. "Add new Email alias" and enter as Alias "*", select the xyz.domain.tld domain from the dropdown and select the actual email address as destination
    Not really sure what you want to achieve by those low/high black/whitelists though.
     
  5. NueX

    NueX New Member

    Thank you very much for your reply. The catchall on a subdomain is what I got working already. The question is really if there is a way to set up spam black/whitelists based on recipients of the mails, too.
    In Confixx for example, this option is part of the spam black/whitelist settings. In ISPConfig I could not find such an option even though I could imagine, it exists on system service level.

    I'm sorry if I did not explain enough what I want to realize, I'll try again: I want to set up a catchall on the subdomain *(AT)xyz.mydomain.com. That's done. Next, I want to filter out all mails to that address based on a spam filter rule *(AT)xyz.mydomain.com. On top of that, with a higher priority, I want to allow/"whitelist" all mailing arriving to addresses of the structure *_xyz(AT)xyz.mydomain.com. Thats all. Allows to invent addresses on the fly and keeps spam out of the inbox.
     
  6. till

    till Super Moderator Staff Member ISPConfig Developer

    You can do that e.g. with sieve filters. add a mailbox where your mails end up and then add the filters on the filters tab or use the custom rules if you want to have a more advanced filter.
     
  7. NueX

    NueX New Member

    Thanks! That seems to be the way to go. Just looked for the feature in the wrong corner.

    Great work, thanks again for ISPConfig!
     

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