Simplenews send mail when specific content is created
One reasonably straightforward way of doing that is with the Rules module.

Assuming there's only a few recipients, not hundreds...

You can use a "Send email" action to conditionally send an email to specified recipients.

Here's some example Rules that can be imported.

1. Basic "Send email" rule

{ "rules_send_email_notification_engineering" : {
    "LABEL" : "Send email notification (engineering)",
    "PLUGIN" : "reaction rule",
    "TAGS" : [ "Mail" ],
    "REQUIRES" : [ "rules" ],
    "ON" : [ "node_insert" ],
    "IF" : [
      { "AND" : [
          { "entity_has_field" : { "entity" : [ "node" ], "field" : "field_department" } },
          { "data_is" : { "data" : [ "node:field-department" ], "value" : "engineering" } }
        ]
      }
    ],
    "DO" : [
      { "mail" : {
          "to" : "example@example.com,example2@example.com",
          "subject" : "New student record created [engineering]",
          "message" : "Sample message"
        }
      }
    ]
  }
}


You could also use the "Send mail to all users of a role" action in Rules to send to all users assigned to the "Engineering department" role, if such a role existed.

Update:

2. Create and send a simplenews newsletter with Rules

Here's how to create and send a newsletter with Rules:

{ "rules_send_email_notification_engineering" : {
    "LABEL" : "Send email notification (engineering)",
    "PLUGIN" : "reaction rule",
    "TAGS" : [ "Mail" ],
    "REQUIRES" : [ "rules", "simplenews_rules" ],
    "ON" : [ "node_insert" ],
    "IF" : [
      { "AND" : [
          { "entity_has_field" : { "entity" : [ "node" ], "field" : "field_department" } },
          { "data_is" : { "data" : [ "node:field-department" ], "value" : "engineering" } }
        ]
      }
    ],
    "DO" : [
      { "entity_create" : {
          "USING" : {
            "type" : "node",
            "param_type" : "simplenews",
            "param_title" : "New engineering student record created.",
            "param_author" : [ "site:current-user" ]
          },
          "PROVIDE" : { "entity_created" : { "entity_created" : "Created entity" } }
        }
      },
      { "data_set" : { "data" : [ "entity-created:status" ], "value" : "1" } },
      { "entity_save" : { "data" : [ "entity-created" ] } },
      { "simplenews_rules_action_send" : { "node" : [ "entity-created" ] } }
    ]
  }
}


You can set other field values on the newsletter node as required with the data_set action.