Just curious, if this is a completely greenfield project, why IMAP instead of JMAP?
This is coming from someone who works with IMAP on a daily basis and has rightfully grown a disdain for it.
- asks you to hand over all information about certain customers.
- accuses you of aiding the illegal activities happening through your service (copyright violations, CP, etc).
Do you have IMAP import? And CardDAV/CalDAV? Edit: also wildcards?