You can use the following details to help you setup your smartphone with Xeretec email
Account Name: Xeretec (or whatever name you wish)
Email Address: firstname.lastname@example.org
Server Address: mail.xeretec.co.uk
Username: <email address>
NB. It's important you include the "xos\" before your username.
NB. If you see an option to enter a domain, you can leave it blank.
NB. You can setup what Syncing you wish to have. For example, you may only want to download the header of each message for the past 2 weeks to help save data.
Specific Product Support
General Microsoft Exchange ActiveSync Support (the above instructions in a more detailed format with links to specific products)
Generic Android (applicable to Samsung Galaxy Android, HTC Android, Motorola Android)
Apple iPhone (instructions from Apple themselves)
HTC Windows 8 Phone (instructions from HTC themselves)
Detailed Windows Phone 8 Setup Guide (Reccomended)
Getting SSL Certificate Issues on your Windows 8 Phone?
Please download and install the below certificate to your Windows 8 Phone and re-setup your Active Sync mail to see if the issue is resolved