Hi Liz –
It sounds like the mailserver software on your Commons server is not configured properly. There are many things that could be going wrong (sending mail is pretty complicated). But from the description you’ve given, my guess is that reverse DNS has not been set up properly. This would result in certain mail servers interpreting your emails as spoofed, trashing them at the level of the firewall (which is why they wouldn’t be in the spam folders).
You have a couple options:
1. Talk to your IT folks about a proper fix. They’ll be able to monitor your outgoing mail logs (usually at /var/log/maillog, but depends on your operating system) and watch network traffic to see if the problem is internal or external. And then they’ll be able to look at your local mailserver configuration to make sure that it’s identifying itself properly to the network.
2. As an interim, you could consider using SMTP for outgoing email. There are a number of plugins for this purpose; I’ve used this one in the past https://wordpress.org/plugins/wp-mail-smtp/. It works by routing outgoing email through an independent SMTP mail server, in the same way that the mail application on your phone or computer connects to a separate server to send mail. This technique will require an existing email account – any one that supplies SMTP will work, which means you can use a jhu.edu address (but not your own!) or something like a gmail.com address. Be careful, though, because most SMTP servers (especially free ones like Gmail) will limit outgoing messages, so that you can only send (say) 500 per day. If the account is handling all outgoing email for a new community, you can quickly burn through this amount.
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