Emails To Customer's Albums Not Going Out.

Tried sending a few emails tonight.  Nothing showing up in "Email Log"

Still can't send invite-email messages to "some" customers.  I was able to get my own personal email address to work (yahoo account) to send the message to myself.  That worked, so I clicked on that SENT email and hit RESEND to type in my customer's gmail address and it went through ok.
**However, inside the PEOPLE tab in a customer's album...I still can't send invite emails directly to that same gmail account(s).
***Also I'm hosted by Saratoga Hosting, which I know is going through lot's of transition right now.?!

Please advise.  Thanks!

I read, and tried all those things.  This has been working fine for 10+ years so I'm wondering why all of a sudden it doesn't work.  From the "invite to view gallery" I can send an email to my personal yahoo account but it won't send an email to gmail accounts.  Why was I able to RESEND the email (from the dashboard) I sent to my yahoo account to a customer's gmail and it worked fine (but it wouldn't work in side the [PEOPLE] tab.  

Do the emails show in Stats -> Email Logs?
if so, Sytist sent them but the server didn't deliver them.

Did you check Settings -> Automated Messages and see if there are pending emails?
If there are pending emails then your cron job is no longer working.