POP3 Connector for Microsoft Exchange and Lotus Domino with Anti-Spam Filter and Anti-Virus Protection: PYTHEAS MailGate

POP3 Connector / POP3 Gateway for Microsoft Exchange 2013 and Microsoft Exchange 2016

Be sure to use PYTHEAS MailGate v.2.72 or later. PYTHEAS MailGate will interact with a Microsoft Exchange 2013 or Microsoft Exchange 2016 server with the Client Access role.

Configure incoming mail flow

1. Connections to the existing Receive Connector

PYTHEAS MailGate downloads messages from a POP3 mailbox and sends them to the "Default Frontend <nom du serveur>" Receive Connector.

2. Allow incoming messages sent to your messaging domain

In the Microsoft Exchange 2013 / 2016 Admin Center, go to Mail flow / accepted Domains.

  • If you have your own messaging domain (like company.com): if you see it in the list, skip the rest of this section. If you don't, add your messaging domain to the list: click on + and create a Authoritative Domain for your messaging domain.
  • If you do not have your own messaging domain (i.e. your users have email addresses like user@your-isp.com), add a Internal relay domain for the domain your-isp.com.

3. Other settings you may want to check

Spam filtering

By default, spam-filtering is not installed. In this case you may skip this section. However, if spam filtering is installed, and you want to use the Microsoft Exchange 2013 / 2016 spam filtering capacities, make sure that messages recognized as spam are always accepted (in the ContentFilterConfig, set the SCLRejectEnabled parameter to false). Beginning with v. 2.74, you may also proceed as described here.

Maximum message size

By default, the Exchange Receive Connector accepts messages with a maximum size of 35 MB. PYTHEAS MailGate will get the maximum message size and will not try to download messages over size. You may want to read this, too...


Configure outgoing mail flow

If you do not want PYTHEAS MailGate take care of outgoing email, you may skip this section and organize outgoing mail flow according to your requirements in Microsoft Exchange 2013 / 2016. On the other hand, if you want PYTHEAS MailGate take care of outgoing mail, please do the following:

Create a new Send Connector

  • If you already have a Send Connector to send email to the Internet, you may consider removing it and create a new one, or modify it according to the instructions below.
  • In the Microsoft Exchange 2013 Admin center, go to Mail flow / Send Connectors. If the list is empty, create a new Send Connector with the following characteristics:
    • Name: ToPytheasMailgate (you can choose any name);
    • Type: Custom;
    • Network settings: choose Route mail through the following smart hosts, then click +, then add the IP address of the machine which will be running the PYTHEAS MailGate Communication Task to the list . You may use if it's on the same machine. Leave the Use the External DNS Lookup settings on the transport server box unchecked.
    • Smart host authentication: choose None
    • Address spaces: click + then enter * (a single asterisk) as the domain name
    • Source Server: click + and add your server to the list.
  • If both Microsoft Exchange 2013 / 2016 and PYTHEAS MailGate run on the same machine, you will need to change the outgoing SMTP port of the Send Connector:
    • Open the Microsoft Exchange Server 2013 / 2016 Management Shell from the Start Menu.
    • Paste the command
      Set-SendConnector -identity "ToPytheasMailgate" -Port:2500
      into the management shell window, and execute it. This will change to outgoing SMTP port to 2500.
    • You may check the new configuration with the following command:
      Get-SendConnector -identity "ToPytheasMailgate" | Format-List
      giving the following result:
      AddressSpaces                : {SMTP:*;10}
      DNSRoutingEnabled            : False
      DomainSecureEnabled          : False
      Enabled                      : True
      Identity                     : ToPytheasMailgate
      MaxMessageSize               : 35 MB (36,700,160 bytes)
      Name                         : ToPytheasMailgate
      Port                         : 2500
      SmartHostAuthMechanism       : None
      SmartHosts                   : {[]}
      SmartHostsString             : []
      SmtpMaxMessagesPerConnection : 20
      SourceIPAddress              :
      UseExternalDNSServersEnabled : False
  • By default, the Exchange 2013 / 2016 Admin Center sets a maximum message size of 35MB for outgoing messages through this send connector ; you can change this limit in the graphical user interface.

Limit de number of outgoing connections

  • In the Microsoft Exchange 2013 / 2016 Admin Center, go to Servers, select your server, and open its properties / Transport Limits. In Outbound connection restrictions, set both the Maximum concurrent connections and the Maximum concurrent connections per domain to 1.
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