If you’re looking for a fix for the Too many Simultaneous Connections error, you’ve come to the right place!
After migration from MS Exchange to Google Apps Gmail, we encountered a number of problems where we had shared access to the same mailbox – e.g a shared customer support mailbox.
We’d set up the account on a number of different PCs so that staff could respond to Customer Support queries from a central mailbox.
All appeared to be fine until one day we started experiencing an error message:
Too many simultaneous connections – message sent from the Gmail server.
A quick search found that Google implements a 10 connection limit to any imap mailbox which caused the problem. (UPDATE: This link now suggests that the limit is 15)
Part of the Thunderbird Settings allow you to specify the number of Cached IMAP connections to use on a mailbox, the default being 5. We changed this to 1 to force all users to stick to a single connection to the shared mailbox.
This can be quickly achieved by changing the ”Right Click Account -> Account Settings -> Server Settings -> Advanced -> IMAP -> Maximum number of server connections to cache” setting.
In theory this should limit each client to 1 connection, allowing up to 10 clients to connect to the same IMAP mailbox. Job Done!