2.1.0

• 1: Update Mailkit to version 3.2.0.
• 2: Adds support for sending emails with attachments. #19
• 3: Update example sdk to .NET 6

2.0.3

• 1: Update Mailkit to version 2.6.0.
• 2: Add optional sender info for SendAsync method #14
• 3: Update to .NET CORE 3.1

Fix Issues #9

1:Update Mailkit to version 2.0.1.
2:Fix Issues #9 about "no authentication error"

2.0.1

1： update mailkit to version 1.18.1.1
2： update project target to netstandard2.0 #8
3： fix mailkit "MailboxAddress" bug #7
4： fix 'TLS-required' #6