To resolve this issue, use one of the following methods, as
appropriate to your situation.
Method 1: Configure a Packet Filter to Permit Outbound Traffic
This issue typically occurs when there is no packet filter defined
to permit outbound SMTP messages from the ISA Server. You must define packet
filters on the ISA Server to permit outbound access for services that run on
the ISA Server. Create a packet filter with the following settings:
Name: descriptive name
Type: Custom
Direction: Outbound
TCP Local port: Dynamic
Remote port: 25
To do this, follow these steps:
- Start the ISA Management snap-in.
To do this,
click Start, point to Programs, point to
Microsoft ISA Server, and then click ISA
Management. - Expand Servers and Arrays, expand your
server, expand Access Policy, right-click IP Packet
Filters, point to New, and then click
Filter.
- In the IP packet filter name box, type a
descriptive name for the packet filter (for example, type Allow SMTP
outbound), and then click Next.
- Click Allow packet transmission if it is
not already selected, and then click Next.
- Click Custom, and then click
Next.
- In the IP protocol list, click
TCP.
- In the Direction list, click
Outbound.
- In the Local port list, click
Dynamic, click Fixed port in the
Remote port list, type 25 in the
Port number box that corresponds to the remote port, and then
click Next.
- Under Apply this packet filter to, keep
the default selection of Default IP addresses for each external
interface on the ISA Server computer unless you have more than one IP
address or external interface on the ISA Server.
If you have more
than one IP address assigned or more than one external interface, you may want
to specify the external IP address for the ISA Server. To do this, click
This ISA server's external IP address, and then type the IP
address. - Click Next.
- Under Apply this packet filter to, keep
the default selection of All remote computers.
If
your Exchange Server is configured to send mail directly to foreign messaging
systems, or if you want to specify a particular smart host, click Only
this remote computer, and then type the public IP address of the
destination computer. - Click Next, and then click
Finish.
Method 2: Verify the SMTP Settings Remote Server
Verify that you can send an e-mail message to the remote mailbox
by using an e-mail client program such as Microsoft Outlook. If applicable,
have the settings on the remote server configured to permit relaying from your
domain and make sure that anti-spam programs that may be installed on the
remote server permit the e-mail message. If you are unsuccessful, you may be
able to specify another SMTP server in the configuration settings of the Alert.