Can’t get SMTP to work

I can’t get SMTP to work in Email Settings.

I’d switched the whole site to use SMTP (using a Gmail SMTP plugin) because some emails to cheaper shared hosting email providers weren’t being delivered. Switching to SMTP for email sending solved that beautifully. All emails across the site now seem to send to all email providers.

Now of course there’s the same issue with Events Manager. So I want to change to SMTP there too.

(The plugin I mentioned handles it with oAuth, whereas your settings don’t.)

I’ve got the following settings:

Notification sender address: the Gmail address of the account we’re using.
Mail sending method: SMTP
Mail sending port: 465
Use SMTP authentication? Yes
SMTP host: ssl://smtp.gmail.com:465
SMTP username: same Gmail address as above
SMTP password: the password for the account

I’ve confirmed the user and pass are correct. I’ve also tried changing port to 587, but no joy.

Do you have any ideas? As as I say, SMTP works fine everywhere else on the site, using the same SMTP account.

Thank you.