Unfortunately this is still happening. I had at least three occurrences the last week, usually after I had been offline for several (peak) hours and then received a lot of mails -- which is a strong indication that we are looking at locking issues. For reference, here is the current procmail rule I am using: :0: INBOX And here is one of those mails as it landed in my inbox: From gp Mon May 11 11:47:44 2015 Mime-Version: 1.0 X-Mailer: GroupWise 2014 SP1 Date: Mon, 11 May 2015 16:59:08 +0200 Subject: RE: Panel at Summit (was: SUSE Overview session for MF sellers at Status: RO X-Status: X-Keywords: X-UID: 9497 Summit) Subject: RE: Panel at Summit (was: SUSE Overview session for MF sellers at Summit) References: <55411433020000380015F956@suse.com> <alpine.LSU.2.20.1504300133211.1897@ghan.fvgr> <55411B23020000380015F961@suse.com> <alpine.LSU.2.20.1505110152180.2744@ghan.fvgr> In-Reply-To: <alpine.LSU.2.20.1505110152180.2744@ghan.fvgr> Message-ID: <55506EC90200003800161308@suse.com> From: ... To: "Gerald Pfeifer" <gp@suse.com> Observe how the multi-line Subject: header is duplicated, and the four headers (Status, X-Status, X-Keywords, X-UID) that Alpine adds are in between.