Note that if you are running your IMSMO server on Linux 64-bit, then you should upgrade IMSMO to 188.8.131.52 prior to upgrading to Domino 9.0.1 Fix Pack 7 (coming soon). See the technotes below for the IMSMO fix list, download links, and info on the Linux 64-bit issue mentioned above.
Download IBM Fix Central: IBM Mail support for Microsoft Outlook (IMSMO)
The upcoming Domino 9.0.1 Fix Pack 7 release (scheduled for Sept 2016) will introduce an API signature change that could potentially cause a crash on both Traveler servers (version 184.108.40.206 and earlier) and IMSMO servers (version 220.127.116.11 and earlier) that are running on Linux 64-bit.
If your Traveler or IMSMO servers are running on Linux 64-bit, it is highly recommended that you upgrade to Traveler 18.104.22.168 (or later) and IMSMO 22.214.171.124 (or later) prior to upgrading your Domino server to 9.0.1 FP7 (or later). Linux 64-bit is the only platform impacted by this issue.