Support
Written by the people who wrote the software.
Try the help center first
Most of what goes wrong is one of a handful of things, and they are all written up at https://app.archivesend.com/help. The storage pages in particular cover the four failures that actually happen: a wrong region, a trailing space in a pasted key, a key that can read but not write, and a bucket name whose capitalization is slightly off.
Then write to us
[email protected]. Tell us what you were doing when it went wrong and what you expected instead. If it involves a delivery or an invoice, the link is more useful than a description.
We are two people in US Pacific time. Expect a reply the same working day, from one of the people who wrote the code rather than from somebody relaying it.
Reporting something urgent
If a client cannot reach a gallery, say so in the subject line and send the link. That jumps the queue, because it is somebody else's customer waiting.