Linux · Mail Server: Dovecot & Anti-Spam

You open the header of a mail signed by OpenDKIM and see a DKIM-Signature line full of one-letter tags — what do a=, d=, s=, bh=, and b= mean?

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More in Mail Server: Dovecot & Anti-Spam

In OpenDKIM, what is the division of labor between signing.table and key.table?

Postfix is running and can already send and receive mail on the server itself, so why do you still need Dovecot for external clients like Thunderbird or a phone?

A client can reach IMAP on port 143 with no encryption at all, yet port 993 refuses any unencrypted connection — what accounts for that difference?

Dovecot's config files run to 1,500-1,800 lines yet almost none of them do anything — how do you see just the settings that actually deviate from the defaults?

Dovecot auto-detects mailboxes and it worked in testing, so why is it still recommended to set mail_location explicitly in 10-mail.conf?

A macOS Mail user keeps hitting 'Maximum number of connections from user and IP exceeded' against your Dovecot server — what limit is being tripped and how do you raise it?

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