for fuzzing the imapserver and smtpserver use different config files than regular tests

otherwise they cannot be running at the same time, they could overwrite each
other's files.

testdata/smtpserverfuzz/domains.conf

@@ -0,0 +1,17 @@
+Domains:
+	mox.example: nil
+	mox2.example: nil
+Accounts:
+	mjl:
+		Domain: mox.example
+		Destinations:
+			mjl@mox.example: nil
+			mjl@mox2.example: nil
+		JunkFilter:
+			Threshold: 0.9
+			Params:
+				Onegrams: true
+				MaxPower: 0.01
+				TopWords: 10
+				IgnoreWords: 0.1
+				RareWords: 2