Complete list of URL's that need to be allowed for IMSVA to function properly:

ERS - Email Reputation (DNS - UDP port 53)
a.mail-abuse.com
q.mail-abuse.com
r.mail-abuse.com

MML - Marketing Message List (DNS - UDP port 53)
m.mail-abuse.com
r.ers.trendmicro.com
 
C&C - CCCA Command & Control traffic (DNS - UDP port 53)
cnc.ers.trendmicro
 
TMASE - InTheCloudHash Spamkey (DNS - UDP & TCP port 53 (TCP for packets larger than 512 byte)
hashserver.cs.trendmicro.com
 
TMASE - CSJ URL domain reputation (DNS - UDP & TCP port 53 (TCP for packets larger than 512 byte)
csj.trendmicro.com
 
TMUFE - WRS Web Reputation (HTTP - TCP port 80)
imsva91-en.url.trendmicro.com
> gslb.url.trendmicro.com.akadns.net
>> trendmicro.com.edgesuite.net
>>> AKAMAI
 
iCRC Smart Scan Server Global Smart Scan Server (TCP port 443)
imsva91.icrc.trendmicro.com
> AKAMAI
 
License and activeupdate
http://imsva91-p.activeupdate.trendmicro.com/activeupdate
https://imsva91-p.activeupdate.trendmicro.com/activeupdate
http://imsva91-en.url.trendmicro.com 
https://imsva910-en.fbs20.trendmicro.com 
https://imsva91.icrc.trendmicro.com/ss 
https://ws3.emailsecurity.trendmicro.com:9000 
https://emsp-sp-us01-wsstatus.trendmicro.com:443/status 
https://licenseupdate.trendmicro.com 
http://licenseupdate.trendmicro.com/ollu/license_update.aspx 
https://olr.trendmicro.com 
https://imsva91-ctp.trendmicro.com

Email Encryption
root.ibe-ta.com                      Port 80
public.ibe-ta.com                   Port 80
ppconfig.ibe-ta.com               Port 80
www.myprivatepost.com       Port 443 and 80
www.privatepost.net              Port 443 and 80