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Specifying a Different SMTP Server to Process Messages from ExpressPro or AirSync Mobile Devices
Document #:10504

Applies To:
  • MailSite 9.2 and later
  • ExpressPro 9.2 and later


Messages sent from MailSite ExpressPro or on a mobile device connected via ActiveSync are placed into the spool such that they bypass any SMTP security and sieve filtering that is performed by SMTPRA. When messages are placed directly into the Spool folder, any filtering performed by SMTPDA will apply.

It is now possible to specify an SMTP server or gateway to process those messages and apply any security filtering required. This SMTP server could be MailSite’s SMTPRA service or a third-party scanning system.

More Information:

This new feature is a way of requesting that all mail generated by ExpressPro and mobile devices linked to MailSite through ActiveSync is to be filed into the spool/untrusted folder. This mail is then routed to the SMTP server specified in the SMTPDA/UntrustedRelayHost and SMTPDA/UntrustedRelayPort properties.

By default these are (for the host) 25 (for the port) which will go to the SMTPRA that is running on this server, but could easily be configured to be some other MTA running on a different server.


Open MailSite\WebServices\WebUI and open web.config with a text editor. Locate the following entry:

<!-- Controls the way mail composed using ExpressPro is processed trusted: If true, then mail is added directly into the "spool/incoming" directory. If false it is added into the "spool/untrusted" for further processing before delivery into the incoming directory-->

<outboundConfiguration trusted="True"/>

Change the OutboundConfiguration value to read "False".

Perform the same change within web.config under MailSite\WebServices\Service.AirSync.

NOTE: You will need to ensure the SMTP server is configured to allow relay for the IP specified within UntrustedRelayHost. If you redirect traffic to the MailSite SMTPRA, then you should ensure is specified within the 'Accept mail for relay from these friendly hosts'

Defining the HostName

There are also two additional optional properties to define the host name that we should route mail to which is delivered into the spool\untrusted folder. This defaults to localhost.
Registry Setup
Incorrectly editing the registry can damage the server, please be sure you know what you are doing
  • Stop the MailSite services.
  • Open the registry and go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SMTPDA\Parameters.
  • Add a DWORD key called UntrustedRelayPort and set this to the port number you wish to use.
  • Add a String key called UntrustedRelayHost and set this to the IP of server you wish to route mail to.
  • Restart the services.
SQL Connector
  • Open the SQL Manager to the MailSite Database.
  • Open the 'MailServerProperties'
Enter the following:

ServiceName PropertyName ServerRoldID PropType PropStringValue
smtpda UntrustedRelayHost 0 1 IP of server to route mail to, defaults to localhost

ServiceName PropertyName ServerRoldID PropType PropIntValue
smtpda UntrustedRelayPort 0 4 Port number, defaults to 25
  • Restart the services

See these other knowledge base documents:
Last revised 2010-12-16

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