certimate-go/certimate

[Bug] Office365 STARTTLS 无法发送邮件 显示TLS失败

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#1,111 opened on Dec 18, 2025

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Description

Release Version / 软件版本

v0.4.9

Description / 缺陷描述

无法发送 测试发送的时候显示

failed to send mail: dial failed: tls: first record does not look like a TLS handshake

Steps to reproduce / 复现步骤

使用一个office365的邮箱链接就会显示，但是可以连接的

root@xxxx:~# telnet smtp.office365.com 587
Trying 2603:1046:c03:e::2...
Connected to smtp.office365.com.
Escape character is '^]'.
220 KL1PR0401CA0023.outlook.office365.com Microsoft ESMTP MAIL Service ready at Thu, 18 Dec 2025 14:47:50 +0000

Contributor guide

Research direction
Investigate the TLS handshake failure with Office365 STARTTLS. Check if the SMTP library correctly issues STARTTLS and handles the server's response, verifying the TLS version and certificate.
Tech stack
go
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GoSMTPTLS
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65