Hello,
An HikaShop guest user do not have any Joomla account assign so it does not have an Acymailing user (which is also related to the Joomla account).
Afterwards the mass action system do not have integration with third party (like Acymailing, HikaSerial or HikaMarket) but that's something we started to improve for a future release.
But Acymailing have an integration with HikaShop so a lot of things are already possible via the generic triggers and the Acymailing feature (like auto-newsletters or filtering).
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.