This test will start a thread to send and retrieve email messages.
An email with an attachment from the file system will be sent.
This test will retrieve the last email message and:

• Save the email's body message and attachments (if any) in the file system.
• Read the email's body message and save attachments (if any) in the file system.
• Read the email's body message using callback function and ignore any attachment.
• Read the email's body message and attachments using callback function.