The Relay property is used to determine if the control will
send the message directly to the wireless service provider's gateway
server, or if the message will be relayed through another mail server.
The default value for this property is False. Setting this property to
True will cause the control to connect to the mail server specified by
the ServerName property, authenticate the client session if
necessary and then submit the message.
When a text message is sent using the SMTP service, the default
action is to attempt to connect directly to the wireless service
provider's gateway server. However, many residential Internet service
providers (ISPs) do not permit their customers to connect to
third-party mail servers and will block the outbound connection. Some
wireless service providers may also reject messages that originate
from residential IP addresses.
To resolve this issue, the developer should allow the user to
specify an alternate mail server that will relay the message to the
wireless service provider. For residential users, this will typically
be the mail server provided by their ISP. For business users, this
will usually be their corporate mail server. The ServerName and
ServerPort properties are used to identify the relay server,
and the UserName and Password properties provide the
credentials to authenticate the client session.