Even I am facing the same problem.
The attachment are not fully visible if the email is big.
Can you provide full version for GroupDocs.Viewer .NET Library for 30 day as trial.
Your trial version only show 2 pages.
Following are the points we are looking in this tool.
1. Email with different types of attachments (pdf,excel,word,csv,attached image as well as inline images) should be able to read.
2.I am sharing the 2 eml file.We want to read different format of email attachment with in the eml file and if the email is big we need to read the trail mail also.
3.Can we convert the eml file to pfd file.
4. Can we provide the access control based on the role for downloading the file in the email.