There was no bounce or notification back with any of these emails.  In one case, I had them resend it to my Gmail account and then forwarded the same message to my balmoralbch.com account on iredmail and it went right through.

I do have zip attachments blocked but nothing was zipped in these emails.

I know that at least two of these came from Microsoft's Outlook 365.  Could there be something different with that?  Such as the image001.emz?

Hi jack,
an emz file is a compressed (z = zipped) emf or wmf file (= enhanced metafile / windows metafile format). Probably wmf files are banned by amavis service of your server.

If you don't want to pass all wmf files you should quarantine banned mails. But if you want to release mails from sql quarantine with amavisd-release, you have to patch amavisd-release (in debian: in /usr/sbin/) or amavisd-new 
o r  you have to set:
$spam_quarantine_method = 'sql:';

And you should notify someone about banned mails:
$banned_admin = "root\@$mydomain"; # to notify an admin (root=postmaster) or another email address
$warnbannedrecip = 1;  # (defaults to false (undef)) - to notify recipients

If you want to inform email senders you have to use D_REJECT or D_BOUNCE as final desteny for banned mails:
$final_banned_destiny     = D_REJECT;

I can't emulate the problem locally - but having made the change to allow zip files, I haven't seen any issues today.  Thank you for all your help.  I'll let you know if things come up in the next few days.

--- Jack