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SmtpConnect(
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LPCTSTR
lpszRemoteHost, |
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UINT
nRemotePort, |
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UINT nTimeout, |
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DWORD
dwOptions, |
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LPCTSTR
lpszLocalName, |
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LPSECURITYCREDENTIALS
lpCredentials |
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The SmtpConnect function is used to establish a
connection with the remote server.
Parameters
- lpszRemoteHost
- A pointer to the name of the remote host to connect to; this
may be a fully-qualified domain name, or an IP address.
- nRemotePort
- The port number the remote server is listening on. A value of
zero specifies that the default port number should be used. For
standard connections, the default port number is 25. For secure
connections, the default port number is 465. If the secure port
number is specified, an implicit SSL/TLS connection will be
established by default.
- nTimeout
- The number of seconds that the client will wait for a response
before failing the operation; a value of zero indicates that the
client should wait an indefinite period of time.
- dwOptions
- A bitmask which specifies one or more options. This parameter
is constructed by using a bitwise operator with any of the
following values:
| Constant |
| Description |
| SMTP_OPTION_EXTENDED |
Extended SMTP commands should be
used if possible. This option enables features such as
authentication and delivery status notification. If this option is
not specified, the library will not attempt to use any extended
features. |
| SMTP_OPTION_SECURE |
This option specifies that the
client should attempt to establish a secure connection with the
server. Note that the server must support secure connections using
either the SSL or TLS protocol. This option is only available in
the Secure Editions of SocketTools. |
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SMTP_OPTION_SECURE_IMPLICIT |
This option is used in addition to
SMTP_OPTION_SECURE. It should be specified when the server expects
an implicit SSL connection. This option should not be used with
ESMTP servers that use the STARTTLS command to initiate a secure
connection. |
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SMTP_OPTION_FREETHREAD |
This option specifies that the
handle returned by this function may be used by any thread, and is
not limited to the thread which created it. The application is
responsible for ensuring that access to the handle is synchronized
across multiple threads. |
- lpszLocalName
- A pointer to a null-terminated string which specifies the
domain name of the local host. This parameter can be NULL or point
to an empty string, in which case the local domain name is
determined automatically from the system configuration. This
parameter should be used if the mail server only accepts messages
from a client that identifies itself using a specific domain
name.
- lpCredentials
- A pointer to a SECURITYCREDENTIALS structure which
is used to establish the client credentials for a secure connection
to the remote server. The function
SmtpCreateSecurityCredentials can be used to create this
structure if necessary. If a standard non-secure connection is
being established, or client credentials are not required by the
server, this parameter can be NULL.
Remarks
The lpszLocalName argument should only point to a
specific domain name if it is absolutely necessary. In most cases,
it is preferable to pass this parameter as NULL or an empty string
and allow the library to automatically determine the correct domain
name to use. Providing an invalid domain name may cause the mail
server to reject the connection.
The dwOptions argument can be used to specify the
threading model that is used by the library when a connection is
established. By default, the handle is initially attached to the
thread that created it. From that point on, until the it is
released, only the owner may call functions using that handle. The
ownership of the handle may be transferred from one thread to
another using the SmtpAttachThread function.
Specifying the SMTP_OPTION_FREETHREAD option enables any thread
to call any function using the handle, regardless of which thread
created it. It is important to note that this option disables
certain internal safety checks which are performed by the library
and may result in unexpected behavior unless access to the handle
is synchronized. If one thread calls a function in the library, it
must ensure that no other thread will call another function at the
same time using the same handle.
Return Value
If the function succeeds, the return value is a handle to a
client session. If the function fails, the return value is
INVALID_CLIENT. To get extended error information, call
SmtpGetLastError.
Requirements
Client: Requires Windows Vista, Windows XP or Windows
2000 Professional.
Server: Requires Windows Server 2008, Windows Server 2003 or
Windows 2000 Server.
Header: Include cstools6.h.
Library: Use csmtpav6.lib.
Unicode: Implemented as Unicode and ANSI versions.
See Also
SmtpAsyncConnect, SmtpAuthenticate, SmtpDisconnect, SmtpInitialize, SmtpUninitialize
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