Since most email servers have strong junk/spam filters by default already, some of these filter emails from @zoiper.com rather quickly and place messages from us directly into the junk/spam folders.
To ensure that you will receive emails from us, you would have to add our domain (@zoiper.com) to your mail server/mail client and whitelist us.
If you are unsure of how to proceed or do not have necessary permissions, contact your system administrator / IT personnel directly.
Short description about whitelisting:
Whitelisting is the practice of explicitly allowing some identified entities access to a particular privilege, service, mobility, access or recognition. It is the reverse of blacklisting.
Spam filters often include the ability to "whitelist" certain sender IP addresses, email addresses or domain names to protect their email from being rejected or sent to a junk mail folder. These can be manually maintained by the user or system administrator - but can also refer to externally maintained whitelist services.
Here's a few guides on how to whitelist for email clients & email service providers:
Thunderbird - https://downtimemonkey.com/blog/how-to-whitelist-an-email-address-in-mozilla-thunderbird.php
Outlook - https://www.lifewire.com/add-address-domain-safe-senders-outlook-1173760
Apple Mail - https://www.lifewire.com/whitelist-domain-os-x-mail-1172857
Gmail - https://www.lifewire.com/how-to-whitelist-a-sender-or-domain-in-gmail-1172106