Unable to Send emails from Outlook

Hello
I reside in Australia and have arrived in the UK for a holiday. The appartment I am staying in has free internet. I have loggon onto their wireless network and have access to the Internet, can receive e-mails but cannot send e-mails??

Last night I was getting this message:
Mail from 81.129.218.54 blocked using Trend Micro oRBL+. Please see https://www.ers.trendmicro.com/reputations/index?ip_address=81.129.218.54

Today I get the follwing message:
Relaying denied. Proper authentication required.

Can someone please help?????