Mail Domain Check Guides

Mail Domain Check GuidesEvidence-led guides for email authentication, transactional delivery, and sender operations.https://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/2026-07-21T00:00:00ZMail Domain CheckCertificate Renewal Succeeded, but SMTP Notification Failedhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/certificate-renewal-succeeded-smtp-notification-failed/2026-07-21T00:00:00Z2026-07-21T00:00:00Z

A source-verified repair path for certificate renewal that commits successfully but is reported as failed when an optional SMTP notification throws.

Cloudflare Email Routing vs Email Sendinghttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/cloudflare-email-routing-vs-email-sending-workers-binding/2026-07-21T00:00:00Z2026-07-21T00:00:00Z

A current architecture guide for inbound Email Routing, restricted verified-destination sending, and outbound Email Sending through Workers, REST, or SMTP.

Cloudflare Email Service: Proofpoint 554 Blockedhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/cloudflare-email-service-proofpoint-554-blocked/2026-07-21T00:00:00Z2026-07-21T00:00:00Z

An evidence-led response path for a Proofpoint 554 rejection of a Cloudflare Email Service shared outbound IP.

Contact Form Says Sent, but No Request Was Madehttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/contact-form-says-sent-no-request-no-email/2026-07-21T00:00:00Z2026-07-21T00:00:00Z

An evidence-led repair path for a contact form that simulates success without a request, durable intake, or a real notification workflow.

Contact Form Submission Saved, but Notification Email Is Missinghttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/contact-form-submission-saved-but-notification-email-missing/2026-07-21T00:00:00Z2026-07-21T00:00:00Z

A source-verified repair path for contact-form intake that succeeds while the administrator notification is skipped, coupled to visitor identity, or fails later in delivery.

SMTP Is in .env, but Docker Compose Password Reset Email Is Not Senthttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/docker-compose-smtp-env-not-passed-password-reset/2026-07-21T00:00:00Z2026-07-21T00:00:00Z

A source-verified diagnostic path for Docker Compose SMTP variables that exist in .env but do not reach the application container.

Nodemailer 535 Authentication Failed in a Payload / Next.js Buildhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/nodemailer-535-authentication-failed-payload-nextjs-build/2026-07-21T00:00:00Z2026-07-21T00:00:00Z

An evidence-led incident path for EAUTH and SMTP 535 during Payload configuration import or a Next.js production build.

Registration Returns 500, but the Account Was Createdhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/registration-returns-500-but-account-created/2026-07-21T00:00:00Z2026-07-21T00:00:00Z

A source-verified state model for preventing optional verification-token or email failures from rewriting a committed account as a failed registration.

Spring Boot Says Verification Email Sent, but No Email Was Senthttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/spring-boot-registration-says-verification-email-sent-but-no-email/2026-07-21T00:00:00Z2026-07-21T00:00:00Z

A source-verified release gate for Spring Boot registration, hashed verification codes, transaction-aware asynchronous email, durable retries, truthful API wording, and single-use verification.

Stellar Horizon Payment Confirmation and Receipt Email Retryhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/stellar-horizon-payment-confirmation-receipt-email-retry/2026-07-21T00:00:00Z2026-07-21T00:00:00Z

An evidence-led state model for Stellar payment confirmation, Horizon retry policy, idempotent receipt jobs, provider acceptance, and recipient delivery.

Symfony Mailer Uses mailer.transports but No Email Arriveshttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/symfony-mailer-transports-ignores-dsn-no-email/2026-07-21T00:00:00Z2026-07-21T00:00:00Z

A source-verified incident path for Symfony Mailer when the configured DSN appears correct, the transport service is plural, and no message reaches the recipient.

Ticket Requester Receives the Creation Email but Not the Resolutionhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/ticket-requester-receives-creation-email-but-not-resolution/2026-07-21T00:00:00Z2026-07-21T00:00:00Z

A source-verified recipient-routing path for ticket systems where creation receipts and resolution notifications reach different actors.

Separate Sending Domain Launch Checklisthttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/separate-sending-domain-spf-dkim-dmarc-warmup/2026-07-20T00:00:00Z2026-07-21T00:00:00Z

A practical evidence checklist for launching a dedicated sending domain or mailbox plus transactional sender with provider-owned SPF, DKIM, DMARC, PTR, warmup, inbox-placement, bounce, complaint, and rollback controls.

Supabase Auth with Brevo: SMTP Account Is Not Yet Activatedhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/supabase-brevo-smtp-account-not-activated/2026-07-19T00:00:00Z2026-07-21T00:00:00Z

A focused incident path for a Supabase Auth 500 paired with Brevo's SMTP account activation error.

Verification Email API Returns 200 or 202 but Nothing Arriveshttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/verification-email-api-200-but-not-received/2026-07-19T00:00:00Z2026-07-21T00:00:00Z

A developer incident path for preserving pending-account truth and proving whether verification work crossed the application, durable queue, provider, SMTP, and receiver boundaries.

First Email Arrived, Later Transactional Emails Are Missinghttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/first-email-arrives-later-transactional-emails-missing/2026-07-20T00:00:00Z2026-07-20T00:00:00Z

A practical boundary map for missing later versions, follow-up message types, and attachments when the first transactional email arrived.

Outlook 550 5.7.1 S3150 Block-List Rejectionhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/outlook-550-5-7-1-s3150-block-list/2026-07-20T00:00:00Z2026-07-20T00:00:00Z

A sender-side response path for Microsoft consumer-mail rejection caused by an outbound sending IP block-list verdict.

SMTP 250 Accepted, but the Email Later Bouncedhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/smtp-250-accepted-but-email-bounced/2026-07-20T00:00:00Z2026-07-20T00:00:00Z

A sender-side design for reporting synchronous SMTP submission and asynchronous per-recipient delivery status without calling relay acceptance final delivery.

Auth0 Verification Email Not Receivedhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/auth0-verification-email-not-received/2026-07-19T00:00:00Z2026-07-19T00:00:00Z

An evidence-led incident path for missing Auth0 verification, reset, passwordless, and OTP messages.

AWS Cognito Verification Email Not Receivedhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/aws-cognito-verification-email-not-received/2026-07-19T00:00:00Z2026-07-19T00:00:00Z

An evidence-led incident path for missing AWS Cognito signup, confirmation, invitation, and password-reset email.

Crypto Wallet Verification Email Not Received in Outlookhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/crypto-wallet-verification-email-not-received-outlook/2026-07-19T00:00:00Z2026-07-19T00:00:00Z

A sender-side incident path for wallet login and OTP email that reaches Gmail but not Outlook, Hotmail, or Live recipients.

Firebase Auth Verification Email Not Receivedhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/firebase-auth-verification-email-not-received/2026-07-19T00:00:00Z2026-07-19T00:00:00Z

An evidence-led incident path for missing Firebase Authentication verification, password-reset, and email-link messages.

Resend Delivered but Email Not Receivedhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/resend-delivered-but-not-received/2026-07-19T00:00:00Z2026-07-19T00:00:00Z

An evidence-led incident path for missing verification, login, and transactional email sent through Resend.

Supabase Auth Email Not Receivedhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/supabase-auth-email-not-received/2026-07-19T00:00:00Z2026-07-19T00:00:00Z

An evidence-led incident path for missing Supabase Auth confirmation, magic-link, OTP, invite, and recovery email.

Web3 Verification Email Not Arrivinghttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/web3-verification-email-not-arriving/2026-07-19T00:00:00Z2026-07-19T00:00:00Z

A sender-side incident workflow for missing wallet login, 2FA, password-reset, and transaction email.

Crypto phishing email header checkhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/crypto-phishing-email-header-check/2026-07-18T00:00:00Z2026-07-18T00:00:00Z

An evidence-based workflow for suspicious wallet alerts, exchange notices, DAO messages, and token emails.

Web3 DMARC Enforcement Checklisthttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/web3-dmarc-enforcement-checklist/2026-07-18T00:00:00Z2026-07-18T00:00:00Z

A practical sender-side checklist for moving Web3 transactional email from DMARC monitoring to enforcement.

Web3 email security checkhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/web3-email-security/2026-07-18T00:00:00Z2026-07-18T00:00:00Z

Free Web3 email security check for wallet alerts, governance notices, transactional email, and newsletters. Verify SPF, DKIM, DMARC, PTR, and MTA-STS without a login.

如何找到 DKIM selectorhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/dkim-selector/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

解释 DKIM selector 的作用、如何从服务商或邮件头找到 selector，以及正确的 DNS 验证方法。

DMARC p=none 应该何时升级https://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/dmarc-p-none/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

解释 DMARC p=none、quarantine、reject 的差异，以及从监控策略安全升级的验证步骤。

Gmail 451 4.7.23: fix the sending IP PTR rate limithttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/gmail-451-4-7-23-ptr-rate-limit/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

Fix Gmail 451 or 421 4.7.23 temporary PTR rate limits. Check the actual sending IPv4 or IPv6 address for reverse DNS and matching forward A or AAAA records.

Fix Gmail 4.7.24 or 5.7.24 suspicious SPF entrieshttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/gmail-451-4-7-24-spf-suspicious/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

Fix Gmail 451 4.7.24 or 550 5.7.24 suspicious SPF entries. Check duplicate records, broken include or redirect targets, broad policies, ptr, and the 10-query limit.

Gmail 4.7.32 / 5.7.32：From 未与 SPF 或 DKIM 对齐https://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/gmail-5-7-32-dmarc-alignment/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

Gmail 4.7.32 / 5.7.32 DMARC alignment 排查指南：核对 From、SPF MAIL FROM 与 DKIM d= 域，修复自定义回信域或 DKIM 签名域。

Gmail 550 5.7.25：PTR record 缺失或正反向不匹配https://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/gmail-550-5-7-25-ptr-record/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

Gmail 550 5.7.25 PTR record 排查指南：从退信提取发送 IP，核对反向 PTR 与正向 A/AAAA 是否互相匹配，并确认配置责任方。

Gmail 550 5.7.26：邮件未通过身份认证https://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/gmail-550-5-7-26-unauthenticated-email/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

Gmail 550 5.7.26 未通过身份认证的排查顺序：区分 SPF hard fail、SPF/DKIM 都未通过和 DMARC policy 拒绝。

Gmail 550 5.7.27：SPF authentication failedhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/gmail-550-5-7-27-spf-failed/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

Gmail 550 5.7.27 SPF authentication failed 排查指南：核对发送 IP、MAIL FROM、SPF 授权路径与 10 次 DNS 查询限制。

Gmail 550 5.7.29：邮件没有通过 TLS 连接发送https://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/gmail-550-5-7-29-tls-required/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

Gmail 550 5.7.29 TLS required 排查指南：定位未加密的出站 SMTP 跳点，检查 STARTTLS 协商、网关回退与邮件服务商日志。

Gmail 550 5.7.30：DKIM authentication failedhttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/gmail-550-5-7-30-dkim-failed/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

Gmail 550 5.7.30 DKIM authentication failed 排查指南：从真实邮件头提取 d= 与 s=，核对公钥、签名域和发送后改写。

Gmail 550 5.7.40：DMARC record or policy missinghttps://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/gmail-550-5-7-40-dmarc-policy/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

Gmail 550 5.7.40 DMARC record or policy missing 排查指南：识别 Author Domain，按 RFC 9989 检查直接记录和父域策略。

Gmail 与 Yahoo 批量发件要求https://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/gmail-yahoo-bulk-sender-requirements/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

Gmail 与 Yahoo 批量发件要求检查表：SPF、DKIM、DMARC 对齐、PTR、TLS、投诉率和一键退订。

MTA-STS 与 TLS-RPT 的组成https://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/mta-sts/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

MTA-STS 与 TLS-RPT 配置指南：DNS 公告、HTTPS policy、mode、MX 模式和报告地址检查。

No DMARC record found：未找到 DMARC 记录https://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/no-dmarc-record-found/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

No DMARC record found 的含义与修复顺序：检查 _dmarc TXT、父域策略继承、RFC 9989 p 与 t 标签和聚合报告。

Outlook 高量发件要求https://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/outlook-high-volume-sender-requirements/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

Outlook.com 每日超过 5,000 封邮件的发件域要求：SPF、DKIM、DMARC 对齐、550 5.7.515 与修复顺序。

SPF PermError：SPF 的 10 次 DNS 查询限制https://mail-domain-check-zac2.coral-ibis-2405.chatgpt.site/guides/spf-10-lookup-limit/2026-07-17T00:00:00Z2026-07-17T00:00:00Z

解释 SPF 10 次 DNS 查询限制、include 与 redirect 预算、PermError 风险及安全修复顺序。