Actually we seem to have confirmed this is another SPF bug. We disabled SPF and messages started working properly again. The 30 is getting added even in the case of these being "ok".
With SPF check:
X-SmarterMail-Spam: Commtouch 0 [value: Unknown], Message Sniffer 0 [code:0], ISpamAssassin 0 [raw: 0], SPF_Fail, DK_None, DKIM_Pass
X-MessageSniffer-ResultCode: 0
X-SmarterMail-TotalSpamWeight: 25
X-MessageSniffer-ResultCode: 0
Without SPF check:
X-SmarterMail-Spam: Commtouch 0 [value: Unknown], Message Sniffer 0 [code:0], ISpamAssassin 0 [raw: 0], DK_None, DKIM_Pass
X-MessageSniffer-ResultCode: 0
X-SmarterMail-TotalSpamWeight: -5
X-MessageSniffer-ResultCode: 0