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Many of these articles are for self-reference. Some are written unedited in the midst of a troubleshooting session. If a few of them appear a bit rough, that’s why.

Postfix – certificate verification failed

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Another email server issue. Coincidentally, I noticed an error in the maillog when sending to my email address. Mar 2 15:13:40 mail postfix/smtp[28811]: certificate verification failed for mail.xxxxx.ca[144.217.111.73]:25: untrusted issuer /O=Digital Signature Trust Co./CN=DST Root CA X3 As it turned out, there was nothing wrong with the certificate or the issuer on the receiving end. […]