Why can't php smtp send emails? How to deal with it?

When using PHP to write email sending scripts, we sometimes encounter the problem of not being able to send emails. One possible reason is that the SMTP server configuration is incorrect. This article will introduce some common SMTP server configuration errors and solutions.

1. Confirm the SMTP server address and port

When using the SMTP service to send emails, you need to configure the SMTP server address and port first. If the configuration is incorrect, the email will be sent. fail. In PHP, you can use the following code to configure the SMTP server:

ini_set("SMTP", "smtp.xxx.com");
ini_set("smtp_port", "25");

Among them, smtp.xxx.com is the address of the SMTP server, and 25 is the SMTP server port number. It should be noted here that the port number of some SMTP servers is not 25. If you do not know the port number of the SMTP server, you can refer to the official documentation of the SMTP server provider to check.

2. Check the authentication settings of the SMTP server

Some SMTP servers require authentication to send emails. If the authentication settings are incorrect, the email will fail to be sent. In PHP, you can use the following code to authenticate the SMTP server:

ini_set("SMTP", "smtp.xxx.com");
ini_set("smtp_port", "25");
ini_set("auth_username", "your_username");
ini_set("auth_password", "your_password");

Among them, your_username is the login username of the SMTP server, and your_password is the login of the SMTP server. password. It should be noted that not all SMTP servers require authentication. If the SMTP server does not require authentication, you can leave the auth_username and auth_password parameters blank.

3. Check the secure connection settings of the SMTP server

Some SMTP servers require a secure connection to send emails. If the secure connection settings are incorrect, the email delivery will fail. In PHP, you can use the following code to set up a secure connection for the SMTP server:

ini_set("SMTP", "smtp.xxx.com");
ini_set("smtp_port", "25");
ini_set("smtp_crypto", "tls");

Among them, tls is a secure connection using TLS, and ssl is a secure connection using SSL . It should be noted that not all SMTP servers require secure connections. If the SMTP server does not require secure connections, you can leave the smtp_crypto parameter blank.

4. Check the firewall settings

Sometimes the failure to send emails is caused by the firewall blocking the SMTP server's request to send emails. To solve this problem, you can try turning off the firewall or adding rules in the firewall that allow the SMTP server to send emails.

5. Check the ISP provider's restrictions

Some ISP providers may limit the number of emails sent or the allowed email size, which may also cause email delivery to fail. In this case, you need to contact your ISP provider to learn about their restrictions so you can better configure your SMTP server.

To sum up, SMTP server configuration errors may cause email sending to fail. When using PHP to write email sending scripts, you need to check the configuration of the SMTP server, including address, port, authentication settings, secure connection settings, etc. If the email fails to be sent, you can refer to the solutions provided in this article to fix it.

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