How to use Application.MailSession in the xlwings API way

The MailSession property of the Application object in Excel’s object model provides access to the MAPI (Messaging Application Programming Interface) mail session for the current user. Through xlwings, this property can be utilized to interact with the email system integrated with Excel, enabling automation of email-related tasks such as sending workbooks or reports directly from an Excel session. This is particularly useful in scenarios where automated email dispatch is required based on data processed in Excel.

Functionality:
The MailSession property returns a MAPI session handle (as a Long integer) if a mail session is active. This handle can be used with Windows API calls or other libraries to perform email operations. However, note that xlwings does not have direct, high-level methods for email; instead, it exposes this property to allow low-level access, which can be combined with Python’s ctypes or pywin32 libraries for extended functionality. It is primarily read-only and indicates whether an email session is logged in.

Syntax in xlwings:
In xlwings, you access the MailSession property via the Application object. The syntax follows the standard xlwings pattern for properties. Since it’s a property, you retrieve its value without parentheses.

import xlwings as xw

# Connect to the active Excel instance or create one
app = xw.apps.active # or xw.App() for a new instance

# Access the MailSession property
mail_session_handle = app.api.MailSession

• Parameters: The MailSession property does not take any parameters.
• Return Value: It returns a Long integer representing the MAPI session handle. If no mail session is active, it may return 0 or an error. In practice, you should check for a non-zero value to confirm an active session.

Example Usage:
Below is a practical example demonstrating how to use MailSession in xlwings to check for an active email session and then perform a simple action, such as sending the active workbook via email using Excel’s built-in SendMail method (which relies on an active mail session). This example assumes you have an email client configured and logged in.

import xlwings as xw

# Start or connect to Excel
app = xw.apps.active

# Check the MailSession property
session_handle = app.api.MailSession
print(f"MAPI Session Handle: {session_handle}")

if session_handle != 0:
    # If a mail session is active, you can proceed with email-related tasks
    # For instance, send the active workbook via email
workbook = app.books.active
    # Use the SendMail method, which requires recipient(s) and optionally subject
    # Note: SendMail is a method of the Workbook object in Excel's object model
    # Here, we specify a recipient email address and a subject
    recipient = "example@domain.com"
    subject = "Report from Excel Automation"

    # Call the SendMail method via xlwings api
    # Parameters: Recipients (as string or array), Subject (optional)
    workbook.api.SendMail(Recipients=recipient, Subject=subject)
    print("Email sent successfully.")
else:
    print("No active mail session found. Please log in to your email client.")