Understanding MHTML and its Challenges in Email Clients
When it comes to sending SSRS reports as email attachments, developers often encounter issues with the rendering of graphs and images. In this article, we’ll delve into the world of MHTML, a format used to embed multimedia content within an HTML document, and explore why it may not work as expected in Thunderbird and Gmail.
What is MHTML?
MHTML stands for MIME-HTML, a format that allows you to embed HTML documents within a MIME (Multipurpose Internet Mail Extensions) message. This enables the recipient to view the embedded content using their email client’s web browser. MHTML was originally designed to support the display of images and other multimedia content in email messages.
How SSRS Reports are Sent as MHTML
In SSRS, reports can be sent as MHTML attachments. When this is done, the report’s content is converted into a format that can be embedded within an HTML document. This allows the recipient to view the report’s graphs and images directly within their email client.
However, not all email clients support the rendering of MHTML attachments. As we’ll discuss in more detail later, Thunderbird and Gmail have different approaches to handling MHTML content.
The Role of Email Clients in Rendering MHTML
To understand why SSRS reports may not work as expected in Thunderbird and Gmail, it’s essential to look at how these email clients handle MHTML attachments.
Thunderbird uses a browser-like interface to view HTML documents, including those embedded within MHTML attachments. However, the lack of support for certain features, such as JavaScript and CSS, can lead to issues with rendering complex graphics like graphs.
Gmail, on the other hand, has a more limited approach to handling MHTML attachments. When an email client sends an attachment in MHTML format, Gmail attempts to render it as HTML content within the body of the email message. If this fails, the attachment is displayed as a file attachment that can be viewed with add-ons.
Workarounds and Alternatives
Given the limitations of Thunderbird and Gmail when it comes to rendering MHTML attachments, developers often seek alternative solutions for sending SSRS reports as email attachments.
1. Sending Reports as HTML Attachments
One common approach is to send the report’s content as an HTML attachment. This allows the recipient to view the report directly within their email client without relying on MHTML support.
To achieve this in SSRS, developers can use the Send as Attachment option and select HTML as Alternative Format. This will convert the report’s content into an HTML document that can be viewed by any email client that supports HTML attachments.
2. Using a Perl Script (unmht)
As mentioned in the Stack Overflow post, there is a Perl script called unmht that can be used to convert MHTML files back into their original format. This allows developers to create a custom solution for sending SSRS reports as MHTML attachments while ensuring compatibility with email clients like Thunderbird.
The basic idea behind using unmht is to take the MHTML file, run it through the script, and then send the resulting HTML content as an attachment in the desired format. This approach requires some manual configuration but can provide a reliable solution for sending complex graphics like graphs.
3. Parsing Data and Sending as HTML
Another alternative is to parse the data from the SSRS report and send it as raw HTML content directly within the email message. This approach eliminates the need for MHTML support altogether, making it compatible with any email client that supports basic HTML rendering.
To achieve this in SSRS, developers can use the Send Data as Text option and specify a custom format for the data being sent. The resulting HTML code can then be inserted directly into the email message body, eliminating the need for an MHTML attachment altogether.
Conclusion
Sending SSRS reports as email attachments can be challenging due to differences in how various email clients handle MHTML attachments. While some solutions like unmht and sending reports as HTML attachments can provide compatibility with Thunderbird and Gmail, they require manual configuration or additional software.
However, by understanding the underlying concepts of MHTML and its limitations, developers can create custom solutions that cater to the specific needs of their SSRS report deployments. By parsing data directly into raw HTML content, developers can ensure that their reports render correctly in any email client that supports basic HTML rendering.
Last modified on 2023-11-10