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Lambda 函数示例

本主题包含用于控制邮件流的 Lambda 函数的示例。

示例 1：删除垃圾邮件

此示例会停止处理包含至少一个垃圾邮件指标的消息。

exports.handler = function(event, context, callback) {
    console.log('Spam filter');
    
    var sesNotification = event.Records[0].ses;
    console.log("SES Notification:\n", JSON.stringify(sesNotification, null, 2));
 
    // Check if any spam check failed
    if (sesNotification.receipt.spfVerdict.status === 'FAIL'
            || sesNotification.receipt.dkimVerdict.status === 'FAIL'
            || sesNotification.receipt.spamVerdict.status === 'FAIL'
            || sesNotification.receipt.virusVerdict.status === 'FAIL') {
        console.log('Dropping spam');
        // Stop processing rule set, dropping message
        callback(null, {'disposition':'STOP_RULE_SET'});
    } else {
        callback(null, null);   
    }
};

示例 2：如果找到特定标头，则继续

只有在电子邮件包含特定标头值时，此示例才继续处理当前规则。

exports.handler = function(event, context, callback) {
    console.log('Header matcher');
 
    var sesNotification = event.Records[0].ses;
    console.log("SES Notification:\n", JSON.stringify(sesNotification, null, 2));
    
    // Iterate over the headers
    for (var index in sesNotification.mail.headers) {
        var header = sesNotification.mail.headers[index];
        
        // Examine the header values
        if (header.name === 'X-Header' && header.value === 'X-Value') {
            console.log('Found header with value.');
            callback(null, null);
            return;
        }
    }
    
    // Stop processing the rule if the header value wasn't found
    callback(null, {'disposition':'STOP_RULE'});    
};

示例 3：从 Amazon S3 检索电子邮件

此示例从 Amazon S3 获取原始电子邮件并对其进行处理。

var AWS = require('aws-sdk');
var s3 = new AWS.S3();
 
var bucketName = '<YOUR BUCKET GOES HERE>';
 
exports.handler = function(event, context, callback) {
    console.log('Process email');
 
    var sesNotification = event.Records[0].ses;
    console.log("SES Notification:\n", JSON.stringify(sesNotification, null, 2));
    
    // Retrieve the email from your bucket
    s3.getObject({
            Bucket: bucketName,
            Key: sesNotification.mail.messageId
        }, function(err, data) {
            if (err) {
                console.log(err, err.stack);
                callback(err);
            } else {
                console.log("Raw email:\n" + data.Body);
                
                // Custom email processing goes here
                
                callback(null, null);
            }
        });
};

示例 4：DMARC 身份验证失败时的退回邮件

如果传入电子邮件的 DMARC 身份验证失败，此示例将发送退回邮件消息。

'use strict';

const AWS = require('aws-sdk');

// Assign the emailDomain environment variable to a constant.
const emailDomain = process.env.emailDomain;

exports.handler = (event, context, callback) => {
    console.log('Spam filter starting');

    const sesNotification = event.Records[0].ses;
    const messageId = sesNotification.mail.messageId;
    const receipt = sesNotification.receipt;

    console.log('Processing message:', messageId);

    // If DMARC verdict is FAIL and the sending domain's policy is REJECT
    // (p=reject), bounce the email.
    if (receipt.dmarcVerdict.status === 'FAIL' 
        && receipt.dmarcPolicy.status === 'REJECT') {
        // The values that make up the body of the bounce message.
        const sendBounceParams = {
            BounceSender: `mailer-daemon@${emailDomain}`,
            OriginalMessageId: messageId,
            MessageDsn: {
                ReportingMta: `dns; ${emailDomain}`,
                ArrivalDate: new Date(),
                ExtensionFields: [],
            },
            // Include custom text explaining why the email was bounced.
            Explanation: "Unauthenticated email is not accepted due to the sending domain's DMARC policy.",
            BouncedRecipientInfoList: receipt.recipients.map((recipient) => ({
                Recipient: recipient,
                // Bounce with 550 5.6.1 Message content rejected
                BounceType: 'ContentRejected',
            })),
        };

        console.log('Bouncing message with parameters:');
        console.log(JSON.stringify(sendBounceParams, null, 2));
        // Try to send the bounce. 
        new AWS.SES().sendBounce(sendBounceParams, (err, data) => {
            // If something goes wrong, log the issue.
            if (err) {
                console.log(`An error occurred while sending bounce for message: ${messageId}`, err);
                callback(err);
            // Otherwise, log the message ID for the bounce email.
            } else {
                console.log(`Bounce for message ${messageId} sent, bounce message ID: ${data.MessageId}`);
                // Stop processing additional receipt rules in the rule set.
                callback(null, {
                    disposition: 'stop_rule_set',
                });
            }
        });
    // If the DMARC verdict is anything else (PASS, QUARANTINE or GRAY), accept
    // the message and process remaining receipt rules in the rule set.
    } else {
        console.log('Accepting message:', messageId);
        callback();
    }
};