arpReach version 1.1.023 and higher allows people whose domain's email is managed by GMail to have bounces and incoming emailed subscriptions processed by arpReach. This was not possible before version 1.1.023 because GMail requires that you connect to it with SSL encryption and arpReach did not have that facility then.
The parameters GMail specifies for connection by IMAP and POP3 are as follows:
IMAP or POP needs to be enabled in the settings of your GMail account. This is done on the 'Forwarding and POP/IMAP' tab of the settings screen in GMail.
arpReach 1.1.023 (and higher) can connect to GMail as above and it needs to do so on the ports shown. However, many web host's firewall blocks outgoing connections on ports 993 and 995, so your web host needs to unblock outgoing connections on those ports before arpReach will be able to connect to it. It is easy to do on a WHM/cPanel server.
Here are the instructions used to do it by logging into my server via SSH and editng the csf.conf file: