Log Message:
- Update cyrus-imapd21 to 2.1.18:
- From the changelog:
> Changes to the Cyrus IMAP Server since 2.1.17
> Fix single byte overflow in imapd annotate extension.
>
> Changes to the Cyrus IMAP Server since 2.1.16
> Fix several security issues in imapd and in mysasl_canon_user.
>
> Changes to the Cyrus IMAP Server since 2.1.15
> Clean up a timeout bug in fud proxy code.
> Fix a number of bugs with the murder and altnamespace handling.
> Detect fork() failures when launching sendmail in lmtpd
> Enable telemetry logging in lmtpd/lmtpproxyd
> Allow APOP to be disabled via an imap option
> Fix reconstruct to handle missing cyrus.header files
> Add the quotawarnkb option
> Update MUPDATE to look for IANA assigned port numbers.