Hi
I am the developer of MailShot Pro, and I'll be happy to answer any general questions here, or help with specific trouble shooting for you on the support pages of our website or by email.
Any contacts you create in MailShot CAN be synched easily between all of your devices using iCloud. They appear in Contacts on the other devices and can be used freely in Mail and other apps (but note that they do not appear in MailShot on other devices too, as you manage each group from only one device at present although you can use the results on all of them)
Occasionally people report that they can't see contacts MailShot created for them, the problem is usually that they are looking in the wrong address book on their device. You have one address book for every different sort of contact sync your device uses, visible in the Contacts app or lists in Mail etc.. The trick if you can't find a contact you are looking for is to tap "groups" at the top left of the contact list, and then select "All Contacts". This will show the contacts from all of your address books at once, and you should now be able to find what you were looking for.
Peter
Solubleapps.com