每次群发电子邮件时使用相同的发件人。调用 Mail API 函数发送电子邮件时，From 标头将设置为与您指定的发件人匹配。
您的发件人地址应该是 Google Workspace 网域中的账号。如果该网域仍在免费试用期内，或用户数量少于六个，那么当 Google 账号发送了过多被标记为垃圾邮件的电子邮件时，可能会暂时被停用。在这些情况下，Mail API 将抛出异常，并显示 Unauthorized sender 错误消息。
使用 DKIM 为您的电子邮件签名，如果您使用 App Engine 发送电子邮件，则需要 G Suite 网域。
发布 SPF 记录，防止垃圾内容发布者假冒您的信包发件人地址。SPF 会验证电子邮件是否从信包发件人 DNS 记录中已发布的 IP 地址发出。App Engine 的信包发件人属于 apphosting.bounces.google.com 网域，因此您的 SPF 记录可能无法用来确定来自 App Engine 的电子邮件是否应该投递。
[[["易于理解","easyToUnderstand","thumb-up"],["解决了我的问题","solvedMyProblem","thumb-up"],["其他","otherUp","thumb-up"]],[["很难理解","hardToUnderstand","thumb-down"],["信息或示例代码不正确","incorrectInformationOrSampleCode","thumb-down"],["没有我需要的信息/示例","missingTheInformationSamplesINeed","thumb-down"],["翻译问题","translationIssue","thumb-down"],["其他","otherDown","thumb-down"]],["最后更新时间 (UTC)：2025-09-04。"],[[["\u003cp\u003eFollow the outlined guidelines to improve inbox delivery rates for Gmail users when sending bulk emails, as recipients marking your email as spam significantly impacts future delivery.\u003c/p\u003e\n"],["\u003cp\u003eEnsure recipients actively opt-in to receive your messages, as purchased email lists and automatically checked opt-in boxes are not considered valid subscriptions, and implement a verification process.\u003c/p\u003e\n"],["\u003cp\u003eProvide clear and easy ways for users to unsubscribe, including prominent links in emails and using the \u003ccode\u003eList-Unsubscribe\u003c/code\u003e header, while automatically unsubscribing users with repeated email bounces.\u003c/p\u003e\n"],["\u003cp\u003eAdhere to RFC 2822 and w3.org standards for email formatting, and avoid tactics that hide the true sender or destination, such as URL shortening services, as it may lead to non-delivery.\u003c/p\u003e\n"],["\u003cp\u003eIf others use your platform to send emails, monitor their behavior and promptly remove those who send spam to adhere to the Google Cloud Platform Acceptable Use Policy and avoid suspension of your application.\u003c/p\u003e\n"]]],[],null,["# Bulk Mail Guidelines\n\nYou must follow these guidelines if your application is sending\nout bulk email, that is, similar messages to numerous recipients. These\nguidelines will help to improve your inbox delivery rate to Gmail users, by\nensuring that all recipients in your distribution list actually want to receive\nthe email. If recipients manually mark your email as spam, then that acts as a\nstrong signal to Gmail to mark future emails from you as spam.\n\nFor more information on sending mail, see the\n[Mail API Overview](/appengine/docs/legacy/standard/php/mail).\n| This API is supported for first-generation runtimes and can be used when [upgrading to corresponding second-generation runtimes](/appengine/docs/standard/\n| php-gen2\n|\n| /services/access). If you are updating to the App Engine PHP 7/8 runtime, refer to the [migration guide](/appengine/migration-center/standard/migrate-to-second-gen/php-differences) to learn about your migration options for legacy bundled services.\n\nAuthentication and identification\n---------------------------------\n\n- Use the same sender for every bulk email. When calling the Mail API function to send email, the `From` header will be set to match the sender you specify.\n- Your sender address should be an account in a [Google Workspace](https://workspace.google.com/) domain. If the domain is still in the free trial period or has less than six users, Google accounts that send too many emails marked as spam might be temporarily disabled. In these cases, the Mail API will throw an exception with an `Unauthorized sender` error message.\n- Sign your email with [DKIM](https://support.google.com/a/answer/174124), which requires a G Suite domain if you are sending using App Engine.\n- Publish an [SPF record](http://support.google.com/a/bin/answer.py?answer=33786) to prevent spammers from spoofing your envelope sender address. SPF verifies that email is sent from an IP address that is published in the DNS records of the envelope sender. App Engine's envelope sender is in the `apphosting.bounces.google.com` domain, so your SPF record may not be used to determine if email from App Engine should be delivered.\n\nSubscription\n------------\n\n- Each user in your distribution list should opt-in to receive messages from you\n in one of the following ways:\n\n - By sending you an email asking to subscribe\n - By manually checking a box on a web form or within a piece of software\n- Using an email address list purchased from a third party is not considered\n opt-in. You also should not set a checkbox on a web form or within a piece of\n software to subscribe all users by default. Users should not be required to\n explicitly opt out of mailings.\n\n- You should verify that the person that signed up by checking the box on the\n web form or in software is actually receiving emails at the address that was\n specified in the form. Verify the user by sending an email that requires them\n to confirm receipt.\n\nUnsubscribing\n-------------\n\n- A user must be able to unsubscribe in one of the following ways:\n - Through a prominent link in the email with no further user interaction other than confirmation.\n - Via an email unsubscribe response.\n- App Engine can only receive email sent to the `[APP_ID].appspotmail.com` domain. Therefore, you will need to set your sender to an address in this domain if you want to automatically handle email unsubscribe responses within App Engine.\n- Use the `List-Unsubscribe` header, which is [supported by the App Engine Mail\n API](#Sending_mail_with_headers).\n- Automatically unsubscribe users whose addresses bounce multiple pieces of email. You can [configure your app to\n receive bounce notifications](#Receiving_bounce_notification).\n- Periodically send email confirmations to users, offering the opportunity to unsubscribe from each list they are signed up for.\n- Explicitly indicate the email address subscribed within your email, because users might forward email from other accounts.\n\nFormat\n------\n\n- Format to [RFC 2822 SMTP standards](http://www.ietf.org/rfc/rfc2822.txt) and, if using HTML, [w3.org standards](http://www.w3.org/standards/techs/html).\n- Attempts to hide the true sender of the message or the true landing page for any web links in the message may result in non-delivery. For example, we recommend that you do not use URL shortener services in bulk email, because these can mask the real URLs contained in the body of your email.\n- The subject of each message should be relevant to the body's content and should not be misleading.\n\nDelivery\n--------\n\n- The following factors will help messages arrive in Gmail users' inboxes:\n - The `From` address is listed in the user's Contacts list.\n - A user clicks \"Not Spam\" to alert Gmail that messages sent from that address are solicited.\n- If you send both promotional email and transactional email relating to your organization, we recommend separating email by purpose as much as possible. You can do this by:\n - Using separate email addresses for each function.\n - Sending email from different domains for each function.\n\nThird-party senders\n-------------------\n\n- If others use your service to send email, you are responsible for monitoring your users and/or clients' behavior. You must remove, in a timely fashion, all users and/or clients who use your service to send spam email. The [Google\n Cloud Platform Acceptable Use Policy](/terms/aup) specifically prohibits spam. Your application can be suspended if you violate this policy, as described in the [Google Cloud Platform Terms of Service](/terms).\n- You must have an email address available for users and/or clients to report abuse, which should normally be `abuse@[YOUR_DOMAIN].com`. You should also monitor `postmaster@[YOUR_DOMAIN].com`.\n- Monitor email sent to app admins. Google may need to urgently contact app admins, for example to notify you of a violation of the Acceptable Use Policy. We can help you to resolve the problems more quickly if you respond promptly to our emails.\n- You must maintain up-to-date contact information in your WHOIS record maintained by your domain registrar, and on [abuse.net](http://abuse.net/).\n\nAffiliate marketing programs\n----------------------------\n\n- Affiliate marketing programs reward third-parties for bringing visitors to your site. These programs are attractive to spammers and can potentially do more harm than good. Please note the following:\n - If your brand becomes associated with affiliate marketing spam, it can affect the email sent by you and your other affiliates.\n - It is your responsibility to monitor your affiliates and remove them if they send spam.\n\nAlternatives to the App Engine Mail API\n---------------------------------------\n\n- You can use a third-party email delivery service provider to send email from App Engine. These services may provide additional features that are not available in the Mail API and may be a better solution for some bulk email senders.\n\nLimits for bulk mail\n--------------------\n\nIf you send too many emails in a short burst, some emails might be silently\ndropped due to Google safety limits. To avoid this, calculate the maximum daily\nrate of emails sent per second by dividing your daily quota by 86,400, the\nnumber of seconds in a day. Do not send bulk email at a rate higher than 50\ntimes the maximum daily rate.\n\nFor more information on other quotas around sending mail, see\n[Quotas and limits](/appengine/docs/legacy/standard/php/mail#quotas_and_limits).\n\nWhat's next\n-----------\n\n- Read the [Mail API\n Overview](/appengine/docs/legacy/standard/php/mail).\n- Learn how to [send mail with the Mail API](/appengine/docs/legacy/standard/php/mail/sending-receiving-with-mail-api)."]]
