Recently, I suddenly noticed that the daily emails from my self-built Baidu Tieba check-in system had stopped, though the check-ins were still happening normally. When I checked the Mailgun interface, the status was all red: The logs showed a long list of bounce messages sent to my Outlook mailbox, such as: The error indicated that Mailgun's entire AS (Autonomous System) had been blacklisted by Outlook. It was now completely unusable. The good news is that many email service providers offer similar services to Mailgun, such as SendGrid. I quickly registered an account on their website, enabled SMTP, and connected my Tieba check-in system, NextCloud, and other services without any issues. The bad news is that my blog uses CommentGun , which I specifically developed for Mailgun,...

In a blog, when the author replies to a visitor's comment, it's difficult for the visitor to notice the reply unless they revisit the page. However, with the comment reply email notification feature, visitors receive an email when the author or another visitor replies to their comment, allowing them to promptly learn about the response. In the widely used WordPress blog system, emails are typically sent via the system's default sendmail, which often ends up in spam folders. Therefore, we usually opt for email services like Tencent, Microsoft, or Google that provide domain-specific email solutions, which require sending emails via SMTP. The issue is that sendmail doesn't natively support SMTP, though this can be resolved using plugins within the blog system. However,...