Add SMTP package

[driaug]

This PR contains the first steps needed to implement an SMTP endpoint into Plunk.

It does include:

• A new smtp package
• All logic needed to take an SMTP request and pass it on to the API

It does not include:

• Certificates or secure endpoints
• Exposed ports etc

It can be used as a base for someone that has slightly more experience with this.

Discussion can be done in #12

[dentroai]

how did you implement the smtp endpoint on the hosted plunk version?

[dentroai]

would there be a disadvantage of creating AWS SMTP credentials of the same AWS SES setup and just bypassing plunk?

I guess plunk would record the emails if we via the plunk smtp right?

[driaug]

Exactly. The main issue is the certificate setup which is needed to create a secure SMTP endpoint.

Bypassing Plunk by going directly through AWS SES is possible but would mean that contacts would not be added to your Plunk project.