Why do my golfers see 'noreply@golfsoftware.com' as the sending email address?  

They can't reply to emails I send out.

It's a DMARC Issue:

DMARC, Domain-based Message Authentication Reporting & Conformance, is an email authentication protocol that allows domain owners to publish a policy statement telling receiving domains what to do if their message fails SPF or DKIM authentication. In an effort to reduce spam and spoofing, email providers have moved to a policy that will reject mail sent from outside of their respective servers. 

This means that if you use a ‘from’ email address of one of these providers, email will be rejected because it was sent from GolfSoftware.com and not the actual provider. In 2014 Yahoo! and AOL published strict DMARC policies, with Gmail slated to follow suit in June of 2018. In fact, this policy will likely become the new standard across all free email providers over time.

To mitigate deliver-ability issues, we encourage the use of your own private domain for email addresses. You can purchase private domains from GoDaddy or other domain companies.

Other third party email providers, like Constant Contact & Mail Chimp, are aware of DMARC issues too.

Possible Solutions:

Add the following line to your emails: 'If you need to reply to this email, send a reply to "xxxxx@xxx.com" (this would be your email address).

Purchase a custom email domain.

Complain to your email provider. Perhaps they'll change their policy.