Type : System.ArgumentException
Source: mscorlib
Method:
NormalizePath
Error: The path is not of a legal form.
Reason: Dim attachment as new System.Net.Mail.Attachment(" ") will cause the error.
空白字符串作为文件路径导致。
Error -- The path is not of a legal form.,布布扣,bubuko.com
Error -- The path is not of a legal form.
原文：http://www.cnblogs.com/xiaoyinxxy/p/3596731.html