registration mail

Hi,

1. First, I would recommend going to the Customers>Emails history menu of HikaShop. There, you can see all the emails sent by HikaShop, including the activation emails.
If you see the emails there, then HikaShop sent the email to the email sending server of your hosting for delivery. If it was not delivered, the reason will be logged in the log file of the email server and your hosting provider should be able to tell it to you.
If you don't see the emails there, then it means that the "user account" email has been deactivated in the System>Emails menu of HikaShop, so please check there.

2. HikaShop uses Joomla messaging system to display the message. It's not HikaShop which displays the message but your Joomla template, which takes it from Joomla messaging system.
The default template of Joomla, and most Joomla templates out there, don't display the messages as popups.
I would recommend you to temporarily switch to the default template of Joomla and try with it. You'll see that the message displays normally.
So, if you see the messages as popups, that's something your template is doing and you should check with your template provider what they recommend.

Hi,

1. Looking at the log, it would seems that there is a problem with the email sending. If you try using the "test" button for the email settings of your Joomla configuration page, does it work ? Do you receive the test email ?
And yes, you should also contact your hosting provider.

3. Yes. You can use translation overrides to change the subjects:
www.hikashop.com/download/languages.html#modify

4. Indeed, PayPal doesn't take into account the current language of the page. It takes into account the preferred language of your browser. I don't think you can change that. However, I don't think it's a case for concern. Usually, people will display your website in their preferred language, which should normally match with the preferred language configured in their browser. Or at least, they should be able to understand both.

Him

1. Then, do you see the email with the activation link in the Customers>Emails history menu of HikaShop ?
You didn't say if you looked there ?
If you do have them there, and since other emails are getting sent, then it's likely that the emails with the activation link are sent too, but they end up getting flagged as spam.
I would recommend testing the registration with www.mail-tester.com/
That way, you can check if something is not configured properly, which would lead to the activation emails getting flagged.