Troubleshooting System.Web.Mail Asp.net C#

Troubleshooting System.Web.Mail

System.Web.Mail
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4.1 A Word About Exceptions (READ THIS FIRST)
4.2 Namespace/COM/DLL Related Exceptions
4.2.1 Error loading type library/DLL.
4.2.10 "Could not access 'CDO.Message' Object - Part 8
4.2.11 "Could not access 'CDO.Message' Object - Part 9
4.2.2 The "SendUsing" configuration value is invalid.
4.2.3 The scary "Could not access 'CDO.Message' object"
4.2.4 "Could not access 'CDO.Message' Object - Part 2
4.2.5 "Could not access 'CDO.Message' Object - Part 3
4.2.6 "Could not access 'CDO.Message' Object - Part 4
4.2.7 "Could not access 'CDO.Message' Object - Part 5
4.2.8 "Could not access 'CDO.Message' Object - Part 6
4.2.9 "Could not access 'CDO.Message' Object - Part 7
4.3 SMTP Protocol/Network Related Exceptions
4.3.1 The server specified in the SmtpServer property is not valid or not available
4.3.10 Can send locally but not externally.
4.3.11 550 x.x.x Unable to relay for xxxxx.
4.3.2 [COMException (0x8004020f): The server rejected one or more recipient addresses."]
4.3.3 Some of emails are rejected by some clients, but not all.
4.3.4 My mail server requires authentication. (503 This mail server requires authentication)
4.3.5 Not a gateway or local host.
4.3.6 The specified protocol is unknown.
4.3.7 The specified protocol is unknown. Part 2
4.3.8 The server response was 452 Filesystem error - message not accepted.
4.3.9 The transport failed to connect to the server.
4.4 Other Problems/Exceptions
4.4.1 How can I stream attachments into the MailMessage?
4.4.2 How can I create an attachment from a string?
4.4.3 Why does System.Web.Mail work in development and not in production?
4.4.4 I keep getting question marks (?'s) in my email, where characters should be.
4.4.5 System.Web.Mail is truncating the message body.
4.4.6 Attachments added to the MailMessge are corrupt.
4.4.7 All of my emails are ending up in the /badmail directory.
4.4.8 System.Web.Mail is corrupting my PDF attachments, what gives?