Usually translate5 uses the standard mail server, that is configured via php.ini, which usually goes through sendmail on Linux.

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How to configure translate5 to only send error mails to certain addresses (or to only send errors of certain log levels) please read here.

TLS Problems

When using a SMTP server with TLS and receiving TLS problems on mail sending, it could be a problem with the TLS encryption.

To test the connection in translate5:

Use t5 system:mailcheck

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To test a raw TLS connection (with gmail server as example):

openssl s_client -connect smtp.gmail.com:25 -starttls smtp

depending on the linux system the path to the systems CAs may be necessary:

openssl s_client -connect smtp.gmail.com:25 -starttls smtp -CApath /etc/ssl/certs 

Connection with error example:

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Sources:

• https://community.letsencrypt.org/t/cert-validation-error-s-unable-to-get-local-issuer-certificate/147914/8
• https://halon.io/blog/how-to-test-smtp-servers-using-the-command-line