Handling TNEF Attachments in Email Messages

Email Messages Containing TNEF Attachments

Transport Neutral Encapsulation Format (TNEF) is a proprietary email attachment format used by Microsoft Outlook and Microsoft Exchange Server. The Aspose.Email API allows you to read email messages that have TNEF attachments and modify their contents. The email can then be saved as a normal message or to the same format, preserving these attachments. This article shows different code samples for working with messages containing TNEF attachments. It also demonstrates how to create TNEF EML files from Outlook MSG files.

Identifying TNEF Attachments in an Email

The following code snippet shows you how to detect whether an email contains TNEF attachments:

from aspose.email import MailMessage

mail = MailMessage.load(data_dir + "message.eml")
is_tnef = mail.original_is_tnef

Reading Emails while Preserving TNEF Attachments

The following code snippet shows you how to read a message and preserve TNEF attachments.

from aspose.email import MailMessage, SaveOptions, EmlLoadOptions, MessageFormat, FileCompatibilityMode

options = EmlLoadOptions()
# This will Preserve the TNEF attachment as it is, file contains the TNEF attachment
options.preserve_tnef_attachments = True

eml = MailMessage.load(data_dir + "message.eml", options)
for attachment in eml.attachments:
    print(attachment.name)

Converting MSG to TNEF

Outlook MSGs sometimes contain information such as tables and text styles that can be corrupted when converted to EML. Creating TNEF messages from such MSG files allows you to retain the formatting and even send such messages via the email clients retaining the formatting. The convert_as_tnef property is used to achieve this. The following code snippet shows you how to create TNEF email from MSG.

from aspose.email.mapi import MapiMessage, MailConversionOptions, OutlookMessageFormat

mapi_msg = MapiMessage.from_file(data_dir + "message.msg")

mail_conversion_options = MailConversionOptions()
mail_conversion_options.convert_as_tnef = True

message = mapi_msg.to_mail_message(mail_conversion_options)

Creating TNEF Email

The following sample code can be used to create an email in TNEF format:

1. Configure file options using the MsgLoadOptions class.
2. Ensure that TNEF attachments in the email are preserved when loading the file by setting options.preserve_tnef_attachments to True.
3. Use the MailMessage.load(eml_file_name, options) method to load the input email file while applying the options configured earlier. This specifically ensures that the loaded email retains TNEF-related information (such as attachments or proprietary Microsoft Outlook formats).

from aspose.email import MailMessage, SaveOptions, MsgLoadOptions, MessageFormat, FileCompatibilityMode

options = MsgLoadOptions()
# The PreserveTnefAttachments option with MessageFormat.Msg will create the TNEF eml.
options.preserve_tnef_attachments = True

eml = MailMessage.load(eml_file_name, options)

Detecting TNEF Messages

The following code snippet shows you how to detect if a message is TNEF. The original_is_tnef property of the MailMessage object is checked to determine if the email was originally in TNEF (Transport Neutral Encapsulation Format). If is_tnef evaluates to True, it means the email contains TNEF encoding, which typically occurs in emails originating from Microsoft Outlook or Exchange.

from aspose.email import MailMessage

mail = MailMessage.load(data_dir + "message.eml")
is_tnef = mail.original_is_tnef