External IMAP account gives strange recursive reading of Trash

[upp]

Could be that this is the wrong forum. But maybe not: while migrating from other mail servers many people end up fighting IMAP problems.
Here's a new one for you.

ZCS up and running nicely, so I tried to sniff on the excellent feature to add an external IMAP account in the web interface. Adding one IMAP account from a quite well known provider went well so I tried to add another less known provider (IP phone company). Test of the account went well but when I clicked "Save" this is what hit me:

system failure: Synchronization of folder 'INBOX/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash' failed, system failure: Unable to add mapping for dataSource Fax, Data truncation: Data too long for column 'remote_id' at row 1 Query being executed when exception was thrown: INSERT INTO mboxgroup19.data_source_item (mailbox_id, data_source_id, item_id, folder_id, remote_id, metadata) VALUES (19, '5a77aef6-165c-409b-a596-b213f3fd4af8', 31318, 31239, 'INBOX/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash', 'd2:lp478:/Fax/INBOX/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash2:uvi1266028127e1:vi10ee') ON DUPLICATE KEY UPDATE data_source_id = '5a77aef6-165c-409b-a596-b213f3fd4af8', item_id = 31318, folder_id = 31239, remote_id = 'INBOX/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash', metadata = 'd2:lp478:/Fax/INBOX/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Trash/Tr ... (truncated)

Chew on THAT one... The IMAP account was actually empty at the time.

Anyone experienced this before?
I'm using a bit old ZCS so maybe it's been fixed.