Re: [exim] 'failed to lock' delivery deferral breaks system …

On 2021-04-23 Ken via Exim-users <exim-users@???> wrote:
[...]
> I manage the email server for a small company in the US. Less than 1000
> received messages per day. A month or two ago I put in place a simple exim
> system filter that removes the 'Friendly Name' from the From: header.

> headers add "X-old-from: $header_from:"
> headers remove "From"
> headers add "From: <${address:$header_X-old-from:}>"

> This works well most of the time and has had good acceptance from the user
> community as part of anti-phishing efforts.

> However, if delivery is deferred to one recipient because of a lock failure
> (example follows) then the final line of the filter does not execute
> correctly, and more than one (perhaps all) recipients receive a message with
> an empty From: header.

> ... defer (-9): failed to lock mailbox /var/mail/redacted (fcntl/flock)

> A pointer to a fix or workaround would be lovely; my current best
> alternative is to switch from mbox to maildir to reduce the frequency of
> delivery deferrals.

Hello,

try wrapping the whole thing in
if first_delivery then
endif

cu Andreas