Sometimes, although Mimecast can connect to the Journal mailbox and authenticate, the actual message extraction may fail due to a message blocking the queue.
Once you have confirmed that no infrastructure or device changes have been made, or if there are any known issues that may prevent the successful extraction of Journal information between the Mimecast and the remote infrastructure, please consider the following:
- Does the Journal mailbox contain large items that might cause a time-out during extraction?
- Does the Journal mailbox contain any items that do not hold a message envelope (when using Exchange Envelope Journaling)?
If you find messages that might be causing the issue (most likely the oldest items in the mailbox), please move them to a subfolder of the inbox and report this back to Mimecast support. Mimecast can then test extraction once more and hopefully continue extracting messages successfully.