I tried using mailx to send out an email from within a notebook and from within a terminal: `echo foo | mailx -s "test" ..@wikimedia.org`
This results in a `failed to open configuration file /etc/exim4/exim4.conf: Permission denied` error.
This would be useful to send out a notification once a long-running query has completed.
**Update September 2018**: This is still not solved, but I noticed that it works when SSHing directly into notebook1003 (and using heirloom-mailx instead of mailx; IIRC mailx is no longer installed by default in newer Debian versions):
```
$ echo foo | heirloom-mailx -s "test" ...@wikimedia.org
```
However it still fails when trying inside a SWAP notebook:
```
In [11]: ! echo foo | heirloom-mailx -s "test" ...@wikimedia.org
2018-09-22 02:51:51 failed to open configuration file /etc/exim4/exim4.conf: Permission denied (euid=3029 egid=500)
2018-09-22 02:51:51 failed to open configuration file /etc/exim4/exim4.conf: Permission denied (euid=3029 egid=500)
2018-09-22 02:51:51 failed to open configuration file /etc/exim4/exim4.conf: Permission denied (euid=3029 egid=500
```