Does Gmail require 2 DKIM signatures?


We are currently set up in Mailwizz with a send-from domain of (as an example) We use our own version of PMTA for SMTP residing on our own cloud server. Mailwizz is installed at and the pmta server is We have been using a single DKIM signature for the parent domain and Gmail says it passes. Also SPF passes.

BUT I was reading in the Guide to PMTA this passage...

PowerMTA now officially supports double DKIM signing a message. This is a direct requirement of Gmail when using their feedback loop. All of the existing dkim-* directives now support the prefix "second", and which are used for the second signature (bottom most one) for the message.

So is it necessary for us to supply 2 DKIM signatures for Gmail to accept our email? I ask because we have had problems with delivery to Gmail as of late.
Is it required for us to supply a DKIM signature from both Mailwizz (the originating server) and the SMTP relay server even if they both have the same Parent domain

Thanks fo any help


New Member
"PowerMTA now officially supports double DKIM signing a message"
double DKIM signing,
do you have the manual of Powermta?