Plugins that send data to Google Apps (email, calendar etc)

Months ago I had several clients that could not receive emails from their WordPress sites despite different form plugins. The common thing was they were using Google Apps email for domains.

Through searching in the forums I found a plugin for form/mail issues https://coffee2code.com/wp-plugins/configure-smtp/ that works fine.

However, I just got an appointment plugin that communicates (via API) with Google Calendar, and I’m having the same exact issues.

The plugin is on website ABC.com. If I have the plugin set to communicate with the Google Apps calendar for the domain ABC.com, the data does not get sent.

If I put the plugin on website at 123.com the same exact plugin settings going to the same exact Google Apps calendar ABC.com, the data gets sent to the ABC.com calendar.

If I change the plugin settings on website ABC.com and have it sending data to a gmail calendar ([email protected]) then it also works.

That plugin that helps with the mail forms is of no use in the situation.

I’ve written to the appointment plugin developer with what I discovered, but I figured it was also something to do with WordPress itself so I thought I’d ask here.