Add step template to support sending email via MailKit

[harrisonmeister]

Background

A customer requested the ability to send an email from Octopus Cloud using an internal only SMTP network. Running this step on a polling worker that can connect to the SMTP server will allow the email to be sent successfully

This step template supports sending an email using the MailKit library, a cross-platform .NET library for IMAP, POP3, and SMTP.

• Support for multiple TO addresses (separated by ,).
• Support for multiple CC addresses (separated by ,).
• Optional support for a separate reply-to address.

This step does not support running on PowerShell: Windows Desktop Edition.

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Required:

• The MailKit and MimeKit packages are installed on the target or worker. If the packages can't be found, the step will attempt to download them from https://www.nuget.org.
• PowerShell Core (including when running on Windows).

Notes:

• Tested on Octopus 2025.1.
• Tested on Windows and Linux with PowerShell Core only.

Results

Customer can send an email using an internal network

Before

After

Pre-requisites

• Id should be a GUID that is not 00000000-0000-0000-0000-000000000000
  • NOTE If you are modifying an existing step template, please make sure that you do not modify the Id property (updating the Id will break the Library sync functionality in Octopus).
• Version should be incremented, otherwise the integration with Octopus won't update the step template correctly
• Parameter names should not start with $
• Step template parameter names (the ones declared in the JSON, not the script body) should be prefixed with a namespace so that they are less likely to clash with other user-defined variables in Octopus (see this issue). For example, use an abbreviated name of the step template or the category of the step template).
• LastModifiedBy field must be present, and (optionally) updated with the correct author
• The best practices documented here have been applied
• If a new Category has been created:
  • An image with the name {categoryname}.png must be present under the step-templates/logos folder
  • The switch in the humanize function in gulpfile.babel.js must have a case statement corresponding to it

[github-actions]

Start Hyponome locally

docker pull ghcr.io/hnrkndrssn/hyponome:main
docker run --rm -p 8000:8080 -it ghcr.io/hnrkndrssn/hyponome:main

Review in Hyponome

[twerthi]

LGTM