Question

Postfix stopped sending emails. I send ticket five days ago and still not response.

Ticket #3465273. The beginning of the failure by the log May 28 03:38:03. During this period, the site code and server settings did not change and Digitalocean executed maintenance on the physical machine hosting my droplet. I need to send mail to register on my site. I losing customers. Before maintenance, emails was sending ok. Not now.

Jun 1 17:55:00 easypackmaker postfix/smtp[30131]: connect to alt1.gmail-smtp-in.l.google.com[142.250.4.26]:25: Connection timed out Jun 1 17:55:00 easypackmaker postfix/smtp[30131]: connect to alt1.gmail-smtp-in.l.google.com[2404:6800:4003:c06::1a]:25: Network is unreachable Jun 1 17:55:00 easypackmaker postfix/smtp[30131]: connect to alt2.gmail-smtp-in.l.google.com[2404:6800:4008:c07::1b]:25: Network is unreachable Jun 1 17:55:00 easypackmaker postfix/smtp[30132]: connect to alt1.gmail-smtp-in.l.google.com[142.250.4.26]:25: Connection timed out Jun 1 17:55:00 easypackmaker postfix/smtp[30132]: connect to alt2.gmail-smtp-in.l.google.com[2404:6800:4008:c07::1b]:25: Network is unreachable Jun 1 17:55:00 easypackmaker postfix/smtp[30133]: connect to alt1.gmail-smtp-in.l.google.com[142.250.4.26]:25: Connection timed out


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KFSys
Site Moderator
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August 30, 2023

Heya,

You’ll need to use SMTP ports rather than port 25. Port 25 is blocked as it’s usually used for malicious content and spam rather than legit mail.

Why we should use SMTP ports -465 or 587

  1. port 465 was designated for SMTP with SSL (Secure Sockets Layer) encryption. SMTPS is a deprecated protocol, but some email servers and clients may still support it. SMTPS uses SSL to encrypt the entire communication between the email client and the email server, including the authentication process and the email data transmission. However, its use is not recommended due to the known vulnerabilities associated with SSL. Most modern email servers and clients prefer using STARTTLS on port 587 instead.

  2. Port 587 (Submission): Port 587 is the default port for the Submission of emails to an email server. The Submission port is used by email clients (such as Outlook, Thunderbird, etc.) to submit outgoing emails to the email server for delivery. It is intended to be used with the STARTTLS command, which is an extension of SMTP that allows for opportunistic TLS encryption. STARTTLS upgrades the connection to a secure encrypted channel, and all communication after the STARTTLS command is encrypted. Port 587 is the recommended port for secure email transmission.

Using either port 465 (SMTPS) or port 587 (Submission with STARTTLS) allows for secure email transmission by encrypting the communication between the email client and the email server. This helps protect sensitive email content, login credentials, and prevents unauthorized access to email accounts during transmission.

In summary, it is recommended to use port 587 with the STARTTLS command for secure email transmission, as it offers better security compared to the deprecated SMTPS on port 465.

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