forwarder.template

AWSTemplateFormatVersion: '2010-09-09'
Description: 'Cloudformation to forward SES email to another address'
Parameters:
  FromAddress:
    Description: Email forwarded from address
    Type: String
  ToAddress:
    Description: Email forwarded to address
    Type: String
Resources:
    SESEmailForwardFunction:
      Type: AWS::Lambda::Function
      Properties:
        Handler: index.handler
        Role: !GetAtt SESEmailForwardRole.Arn
        Timeout: 30
        Environment:
          Variables:
            from_address: { "Fn::Sub": [ "${FromAddress}", { "FromAddress": {"Ref" : "FromAddress" }} ]}
            to_address: { "Fn::Sub": [ "${ToAddress}", { "ToAddress": {"Ref" : "ToAddress" }} ]}
        Code:
          ZipFile: !Sub |
            var AWS = require('aws-sdk');
            var forwardFrom = process.env.from_address;
            var forwardTo = process.env.to_address;  
            exports.handler = function(event, context) {
                var msgInfo = JSON.parse(event.Records[0].Sns.Message);
                
                // don't process spam messages
                if (msgInfo.receipt.spamVerdict.status === 'FAIL' || msgInfo.receipt.virusVerdict.status === 'FAIL') {
                    console.log('Message is spam or contains virus, ignoring.');
                    context.succeed();
                }

                var email = msgInfo.content, headers = "From: "+forwardFrom+"\r\n";
                headers += "Reply-To: "+msgInfo.mail.commonHeaders.from[0]+"\r\n";
                headers += "X-Original-To: "+msgInfo.mail.commonHeaders.to[0]+"\r\n";
                headers += "To: "+forwardTo+"\r\n";
                headers += "Subject: Fwd: "+msgInfo.mail.commonHeaders.subject+"\r\n";
            
                if (email) {
                    var res;
                    res = email.match(/Content-Type:.+\s*boundary.*/);
                    if (res) {
                        headers += res[0]+"\r\n";
                    }
                    else {
                        res = email.match(/^Content-Type:(.*)/m);
                        if (res) {
                            headers += res[0]+"\r\n";
                        }
                    }
            
                    res = email.match(/^Content-Transfer-Encoding:(.*)/m);
                    if (res) {
                        headers += res[0]+"\r\n";
                    }
            
                    res = email.match(/^MIME-Version:(.*)/m);
                    if (res) {
                        headers += res[0]+"\r\n";
                    }
            
                    var splitEmail = email.split("\r\n\r\n");
                    splitEmail.shift();
            
                    email = headers+"\r\n"+splitEmail.join("\r\n\r\n");
                }
                else {
                    email = headers+"\r\n"+"Empty email";
                }
            
                new AWS.SES().sendRawEmail({
                    RawMessage: { Data: email }
                }, function(err, data) {
                    if (err) context.fail(err);
                    else {
                        console.log('Sent with MessageId: ' + data.MessageId);
                        context.succeed();
                    }
                });
            }
        Runtime: nodejs12.x
    SNSEmailReceiveTopic:
      Type: AWS::SNS::Topic
      Properties:
        Subscription:
        - Endpoint:
            !GetAtt SESEmailForwardFunction.Arn
          Protocol: lambda
    SESEmailForwardRole:
      Type: AWS::IAM::Role
      Properties:
        AssumeRolePolicyDocument:
          Version: '2012-10-17'
          Statement:
          - Effect: Allow
            Principal:
              Service:
              - lambda.amazonaws.com
            Action:
            - sts:AssumeRole
        Path: "/"
        Policies:
        - PolicyName: SESEmailForward
          PolicyDocument:
            Version: '2012-10-17'
            Statement:
            - Effect: Allow
              Action:
              - logs:CreateLogGroup
              - logs:CreateLogStream
              - logs:PutLogEvents
              Resource: arn:aws:logs:*:*:*
            - Effect: Allow
              Action:
              - ses:SendEmail
              - ses:SendRawEmail
              Resource: "*"
    SNSLambdaInvokeRole:
      Type: AWS::Lambda::Permission
      Properties:
        Action: lambda:InvokeFunction
        Principal: sns.amazonaws.com
        SourceArn:
          Ref: SNSEmailReceiveTopic
        FunctionName:
          !GetAtt SESEmailForwardFunction.Arn
Outputs:
  LambdaFunction:
    Value: { Ref : SESEmailForwardFunction }