...didn't get any, but I found some via an unfortunate client, who was doing this via a CRM without setting any sort of domain authentication up for their sender (I do data migrations at my day job, so I see everyone's skeletons...)
tl;dr: bounce rate will be about 45-50% over time if you don't set up any sort of DKIM or SPF records, varying slightly depending on your recipients, but it's the IMPORTANT PEOPLE you can't email.
Excerpt below, email server which rejected the message.
Email Bounced | Email Server
---------------------------------------
@cbmove.com usb-smtp-inbound-1.mimecast.com.
@pattonboggs.com eu-smtp-inbound-1.mimecast.com.
@montgomerycollege.edu mx0a-0016b401.pphosted.com.
@iri.org us-smtp-inbound-1.mimecast.com.
@stemedcoalition.org us-smtp-inbound-2.mimecast.com.
@bipc.com us-smtp-inbound-1.mimecast.com.
@dickblick.com us-smtp-inbound-1.mimecast.com.
@student.american.edu mx0a-00240c01.pphosted.com.
@cbf.org us-smtp-inbound-1.mimecast.com.
@binghamt.gannett.com us-smtp-inbound-1.mimecast.com.
@hhlaw.com eu-smtp-inbound-2.mimecast.com.
@pattonboggs.com eu-smtp-inbound-1.mimecast.com.
@iri.org us-smtp-inbound-1.mimecast.com.
@tmgcustommedia.com us-smtp-inbound-1.mimecast.com.
@washington.goethe.org mx02.goethe.de.
@nbcuni.com mxb-00176a04.gslb.pphosted.com.
@jonesday.com mxb-00393202.gslb.pphosted.com.
@intelsatgeneral.com mxb-0056a401.gslb.pphosted.com.
@qga.com mxa-00173601.gslb.pphosted.com.
@wpost.com mxb-001a3c01.gslb.pphosted.com.
@nbcuni.com mx0a-00176a04.pphosted.com.
@tr.com mxb-00160c04.gslb.pphosted.com.
@arts.ri.gov mx0b-00137801.pphosted.com.
@readexpress.com mxa-001a3c01.gslb.pphosted.com.
@icloud.com mx02.mail.icloud.com.
@readexpress.com mxa-001a3c01.gslb.pphosted.com.
@nbc.com mxa-00176a04.gslb.pphosted.com.
@wellsfargoadvisors.com mxa-00004003.gslb.pphosted.com.
@american.edu mx0b-00240c01.pphosted.com.
@chron.com mxa-0018d701.gslb.pphosted.com.
@na.ko.com mxa-0037a502.gslb.pphosted.com.
@bbandt.com mxb-0058fb01.gslb.pphosted.com.
@exxonmobil.com mxa-00016305.gslb.pphosted.com.
@dcist.com mx0a-00240c01.pphosted.com.
@k12.com mxa-00678201.gslb.pphosted.com.
@stanford.edu mxb-00000d07.gslb.pphosted.com.
@ge.com mx0a-00176a02.pphosted.com.
@american.edu mx0b-00240c01.pphosted.com.
@dynetics.com mxa-00336402.gslb.gpphosted.com.
@washpost.com mxa-001a3c01.gslb.pphosted.com.
@pnc.com mxb-000ade01.gslb.pphosted.com.
@vh1staff.com mxa-00262c01.gslb.pphosted.com.
@hosthotels.com mxa-00320801.gslb.pphosted.com.
@dc.gov dc-gov.mail.protection.outlook.com.
@dc.gov dc-gov.mail.protection.outlook.com.
@arenastage.org arenastage-org.mail.protection.outlook.com.