I think a better way to go, as discussed in https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=248387 is to just remove the dh.param setting:

Looks good.

The change (with some minor tweaks) has been committed to the upstream open source distribution and will be part of the next vendor import into FreeBSD.

If the current code works, I'd prefer to put this change in the upstream first and import it into the FreeBSD source on the next sendmail import. If this is causing breakage now, then we can proceed.

I've added the fix upstream using the following diff (slightly different than your diff):

I'll make the change in the upstream vendor version.

It is fine to commit as is. One thing to consider would be simplifying:

Setting action to request change to a port diff instead of a base diff.

I would prefer not to modify the base sendmail as it is a direct import from the upstream vendor source. Modifications like this belong in either a milter port or the sendmail port.

Thank you, looks good to me. I'll add it to the upstream source for the next release.

In D3302#67565, @garga wrote:

solaris11.m4 is already there - https://svnweb.freebsd.org/base/head/tools/build/mk/OptionalObsoleteFiles.inc?view=markup#l6573

I also plan to MFC this to stable/10, do you approve the MFC too?

Thanks for catching this -- I'll add this file to my list of files to hit on updates.