Title: Show OpenSMTPD queue and force sending queued mails
       Author: Solène
       Date: 24 October 2018
       Tags: opensmtpd highlight openbsd
       Description: 
       
       If you are using [opensmtpd](http://man.openbsd.org/smtpd) on a device
       not
       always connected on the internet, you may want to see what mail did not
       go, and
       force it to be delivered **NOW** when you are finally connected to the
       Internet.
       
       We can use [smtpctl](http://man.openbsd.org/smtpctl) to show the
       current queue.
       
           $ doas smtpctl show queue
          
       1de69809e7a84423|local|mta|auth|so@tld|dest@tld|dest@tld|1540362112|154
       0362112|0|2|pending|406|No MX found for domain
       
       The previous command will report nothing if the queue is empty.
       
       In the previous output, we see that there is one mail from me to
       dest@tld which is pending due to "NO MX found for domain" (which is
       normal as I had no internet when I sent the mail).
       
       We need to extract the first field, which is 1de69809e7a84423 in the
       current example.
       
       In order to tell opensmtpd to deliver it now, we will use the
       following command:
       
           $ doas smtpctl schedule 1de69809e7a84423
           1 envelope scheduled
           $ doas smtpctl show queue
       
       My mail was delivered, it's not in the queue anymore.
       
       If you wish to deliver **all** enveloppes in the queue, this is as
       simple as:
       
           $ doas smtpctl schedule all