Form submits but email not sending

Try installing a plugin like Flamingo and see if they are captured. From there you’ll establish if there is actually data being processed.
If emails never arrive and they’re being saved into Flamingo then you’ll need to check your junkmail folder. Failing that consider an SMTP extension for WordPress Mail.

Plenty of possible causes, most likely not related to CF7

For me, the emails are captured, but no email send out. Yesterday we updated to 4.8.1 then no more emails. Today I updated to 4.9 but still no emails…

Look at here: https://www.ads-software.com/support/topic/send-form-is-no-longer-working/ and here: https://www.ads-software.com/support/topic/submit-button-spins/