The standard format for storing email is the MIME format (Multi-Purpose Internet Mail Extensions). Virtually all human-written Internet email and a fairly large proportion of automated email is transmitted via SMTP in MIME format.
To open and decode a MIME file you need an email client installed on your computer that will allow you to read the message, view the inline images that are embedded within and to extract the attachments.
An email can also contain linked images that are not embedded in the message that need to be downloaded first in order to display them. On the long term those links may no longer be available and the email would be incomplete.
An alternative format for storing email messages is PDF (Portable Document Format). PDF is a file format used to present documents in a manner independent of application software, hardware, and operating systems. It was developed in the early 1990s as a way to share documents, including text formatting and inline images, among computer users of disparate platforms who may not have access to mutually-compatible application software.
Because a PDF file can contain images, attachments, XML data, fonts and the original layout in a self-contained document, it makes for a quite convenient format for storing email messages.
Storing email in the PDF format has the following advantages:
- PDF is a standard format used for archiving. It has been release by Adobe as an open standard on July 2008 ( ISO 32000-1:200).
- There is no need to download anything. The PDF document contains everything.
- The document is readable and similar to the original containing text, images and layout.
- The document can be read by just clicking on the file.
- Email attachments that are embed within can be opened and saved using the PDF reader
- When the email headers, email data and attachments are embedded in the PDF file, it can be used as a source to export back and convert to other formats and targets.
- It can be encrypted for security
- A PDF file can be digitally signed for authentication .
In conclusion, PDF can be used for long term storage of email. Software like MsgExtract can be used to download the linked images, embed the email metadata, images, headers and attachments inside the PDF file.
If you are concerned with email readability, or you need to have your files signed and encrypted PDF is a format to consider. The advantage of opening the PDF files by clicking on them and having the complete body with images and also the attachments makes it quite an attractive format.
If you care more on preserving your email messages regardless of the email readability you can’t go wrong with the MIME format.