[Test] Add test of SMTP related functionalities

[fmigneault]

Description

All features that depend on SMTP for sending notification emails are mostly untested when new versions are developed.
Validation should be accomplished with proper tests and mock of a server to "send emails".

References

Potential solutions for mocking:

• https://stackoverflow.com/questions/5811425/dummy-smtp-server-for-development-purposes
• https://muffinresearch.co.uk/fake-smtp-server-with-python/