Email not going to orcon or iserve servers

Seeing the following on all our mail servers for any emails where mx is either orcon or iserve

2018-01-26 17:30:19 H=mx1.orcon.net.nz [60.234.4.47] SMTP error from remote mail server after end of data: 451 4.3.0 Error running virus scanner: swerr2018-01-26 17:30:19 H=mx4.orcon.net.nz [60.234.4.46] SMTP error from remote mail server after end of data: 451 4.3.0 Error running virus scanner: swerr2018-01-26 17:30:19 H=mx2.orcon.net.nz [60.234.4.48] SMTP error from remote mail server after end of data: 451 4.3.0 Error running virus scanner: swerr

Anyone else seeing problems?

BTW we have multiple mail servers at different locations and all appear to have the same problems