If you also have systems running Exim, patch your Exim systems.

[ Largely off-topic here, but perhaps some readers will benefit. ]

If, in addition to any Postfix systems you may have, you also have
some Exim systems, please make sure to upgrade them to 4.92 promptly:

Qualys Security Advisory
The Return of the WIZard: RCE in Exim (CVE-2019-10149)

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[ For those not old enough to remember, "WIZard" is an allusion to
the Morris Worm of 1988. ]

And now back to your regular programme...