forwardings to multiple addresses being treated as a single address with a comma

[Jim At Your Service]

In postfix 2.9.6, we used hundreds of multiple forwardings with wildcards
as the first component, such as "@theidsp-network.inter-realm.net,<email address hidden>".

We are seeing these forwards being treated as a single address.
See these log snippets which show the lookup of the forward
and then the to= being generated with a comma in the address.

Apr 14 10:45:17 mail7-057 sslmx/smtpd[8640]: mail_addr_find: <email address hidden> -> @theidsp-network.inter-realm.net,<email address hidden>
...
Apr 14 10:45:17 mail7-057 postfix/smtp[8669]: 55E65C895: to=<"<email address hidden>,<email address hidden>>, orig_to=<jimays@theids
p.net>, relay=mail7-052.idsp56.net[192.168.56.52]:52025, delay=0.06, delays=0.01/0.02/0.01/0.02, dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as 5F628
A882)

I originally posted this issue about a year ago at https://serverfault.com/questions/1098631/after-postfix-3-5-6-upgrade-virtual-alias-maps-to-multiple-recipients-are-treat after upgrading to postfix 3.5.6 from 2.9.6. There are many more details at that link, including a log from postfix 2.9.6 showing that things worked correctly then.

A workaround was amazingly-to-me found by user anx that we could change the first items in our forwards to a single email from a wildcard, so I changed all forwards to use specific addresses such as "<email address hidden>,<email address hidden>" and things worked fine with that workaround.

I intended to post the issue upstream and never got that far since the workaround was working.
So now I am finally doing the right thing.

[Jim At Your Service (jimays)]

The workaround does not work for wildcard redirects. For example, I was forwarding "@theidsp.net" to "@theidsp-network.inter-realm.net,<email address hidden>" so Jim would get a copy of any catch-all emails also forwarded to @theidsp-network.inter-realm.net. There is no real workaround in this case because the first component must remain a wildcard to handle catchall emails. So I had to just change to a single address @theidsp-network.inter-realm.net" and Jim just doesn't get a copy.