Slack App installed via CLI in our Enterprise Grid failing to send emails

We have an Enterprise Grid plan and need to send emails via SMTP from our hosted CLI Slack app (App ID: A071YDWMBG8) that forwards messages in a channel to our ticketing system.

This solution used to work until recently, when we realised it stopped working with an SMTP error

Current Issue:

Error: "NotCapable: Requires net access to smtp.gmail.com:587." error: Uncaught (in promise) NotCapable: Requires net access to "smtp.gmail.com:587", run again with the --allow-net flag conn = await Deno.connectTls({ outgoingDomains configured in manifest SMTP ports (587, 465) are blocked by the platform Steps taken: We used the --allow-net flag, yet no success

Please help