Internal emails marked as spam

Discussion in 'Mail Gateway: Installation and configuration' started by adam.sage, Feb 11, 2019.

  1. adam.sage

    adam.sage New Member

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    Some of my internal emails are not being delivered. In the blocked notification I see the major parts of the score are from:

    RCVD_IN_PBL 3.558 Received via a relay in Spamhaus PBL
    RDNS_NONE 1.274 Delivered to internal network by a host with no rDNS

    I checked my domain and it is not listed on any blacklist. What is going on here?
     
  2. dcsapak

    dcsapak Proxmox Staff Member
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    seems one of your hosts is on a blacklist?
     
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  3. adam.sage

    adam.sage New Member

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    It appears only people outside of our network are getting blocked. My exchange server only accessible over the internet via http and https (so activesync) and all emails are being delivered to the Proxmox gateway with internal IP addresses from exchange. My Proxmox public IP is not on a blacklist. I thought the exchange server would be the IP address used for checking spam, why would Proxmox be using the client IP address?
     
    #3 adam.sage, Feb 12, 2019
    Last edited: Feb 12, 2019
  4. Stoiko Ivanov

    Stoiko Ivanov Proxmox Staff Member
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    Do I understand you correctly: Your users are sending mails from 'outside' (the internet) to the Exchange-Server through PMG?
    In that case these mails are treated as though they are received from any other mail-server - and if that user happens to be using an IP which is Blacklisted (because they are sharing it with others and some spam originated from there) then they get blocked.

    Usually you want your 'users' to not send their mails to your server via port 25, but rather through and TLS-encrypted, authenticated connection (usually on port 587 with the submission service) - this needs to be configured on the mailserver responsible for the mails - Exchange in your case
     
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  5. adam.sage

    adam.sage New Member

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    The users are outside of our network (internet), but the emails are being sent to the exchange server via outlook or smartphone which is then sending the emails through the proxmox gateway. The users are not sending to the gateway directly.
     
  6. heutger

    heutger Active Member

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    This both triggers look like your sending server is not homed well to send outgoing mails. PBL is the dialup IP list, so your sending server seems to be in an IP address block, which is defined as dialup IP address and should not been used to send mails to the internet. You may try to whitelist your servers IP address, so that it get not checked by this list. Same your server seems not to have a reverse DNS record. This may also occur for IP addresses of your dialup (e.g. DSL) provider, which you shouldn't use for sending mails directly to other internet mail servers.
     
  7. adam.sage

    adam.sage New Member

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    Like I said in my last reply, emails are sent through our Exchange 2013 server to the Proxmox gateway. There should be no public IP addresses involved. There must be something exchange is doing to insert the public IP address of the client in the headers, but it still doesn't make sense why only clients outside of our network are having this issue. I guess I have some digging to do if no one here has heard of this before.
     
  8. heutger

    heutger Active Member

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    Yes, sounds really strange.
     
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