To fix bug 20310 a new property com.openexchange.imap.maxNumConnections is introduced which specifies the max. number of connections allowed being established concurrently for a user to an IMAP server. In opposite to property com.openexchange.imap.maxNumExternalConnections this applies to primary accounts, too, and overrides com.openexchange.imap.maxNumExternalConnections behavior if it specifies a lower value.

The default is 0 meaning infinite connections may be established.

Here the property and its description from imap.properties file:

# The max. number of connection allowed being established for a user to an IMAP server
# Note: This setting overrides possibles restrictions specified through property com.openexchange.imap.maxNumExternalConnections if
# this property's value is less than the other one.
# Less than or equal to zero means infinite.
com.openexchange.imap.maxNumConnections=0