Why can't I access my work email on my phone (both W10 and 8.1)?

[Windows Central Question]

Cannot acess work email on phone (both w10 and 8.1)

I have tried accessing my work email remotely on my phone via activesync. It will not work either through outlook or the remote web access (remote.companyname.co.uk), however the latter works on my PC. All login details have been confirmed as correct by 2 members of the IT department.