Ok, I've done that. Still no joy.
Plus, I've now set up a fresh WP install on the destination web host the theme I'm developing will use and added VFB and WP-Mail-SMTP. I then put in the smtp details of the host. I get the same issues. I only receive a contact form email or smtp test email in 1 out of the 4 destination addresses I tried.
I don't know if this helps but the address the email gets sent to is an Apple .mac.com, whereas 2 of the 3 other addresses that receive nothing are one.com accounts.
Can anyone help pin-point where the issue is here please? Is it the servers of the addresses that don't receive the emails fault (i.e. one.com)? Or it is the servers where WP are installed? (i.e. my local MAMP, or the client's web-host).
All this is a bit above my head and I just need to know that the form can send emails to the client before I go live with the site. Is trying another form plug-in such as Gravity Forms going to be worth the expense and time? Or is this simply an issue with servers?
I'm confused. :-(