Tag Archives: SMTP

Networking, OS

Fix POP/SMTP not working in Sophos UTM

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It all started with an innocent enough e-mail:

Data Disk is filling up - please check. Current usage: 100%

I couldn’t find any clear information about what to do about this on Sophos’ forums. My data disk was full. What to do?

I can tell you what not to do – delete random files. I thought my solution would be to log into the UTM’s console and run a du -hsx /* to see where the space was. I found a large folder inside /var/storage – /var/storage/cores/httpd.16438. I removed it, because why not?

It turns out that did some weird things to my UTM. After removing that folder I kept getting spammed with these e-mails, once every hour:

Pop3 proxy not running - restarted

It took me a while to realize, but this also meant all e-mails relayed to the UTM were not being delivered. The entire POP/SMTP subsystem of the Sophos UTM was hosed. I could not find anything on the Sophos forums. After scratching my head I decided to have a deeper look at the logs. From the command line I issued

ls -ltr /var/log

and began reading the most recent logs.

pop3.log let me know what the problem was:

pop3proxy[9270]: Can't connect to database, retrying in 10 seconds: could not connect to server: Connection refused

I could not find any useful fixes for this error. I kept digging.

selfmon.log wasn’t much help other than to confirm that pop3 was having some serious issues. It was an endless abyss of repeated error messages:

selfmonng[3818]: W NOTIFYEVENT Name=pop3proxy_running Level=INFO Id=117 suppressed
...
selfmonng[3818]: W actionCmd(+): '/var/mdw/scripts/pop3 restart'

system.log put me on the right track:

ulogd[5107]: pg1: connect: could not connect to server: No such file or directory

 

Finally, we’re getting somewhere! After some searching I learned that pg1 is the postgresql database Sophos uses. I found a way to rebuild from this forum post.

One simple command did the trick:

/etc/init.d/postgresql92 rebuild

This rebuilt the postgresql database that I apparently corrupted when I removed files with reckless abandon. My e-mails work again!

Web

Configure Sophos UTM to forward e-mail for internal clients

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If you’re in a situation like mine you have an ISP which stubbornly blocks port 25. You can get around this by using SSL/TLS of course but configuring each server can be a pain. The solution, in my case, is to turn my UTM into an e-mail relay server and simply have each node point to it for SMTP.

The process wasn’t as straightforward as I had hoped. Below are the steps to accomplish this:

First, enable the SMTP proxy by going to E-mail Protection / SMTP.

Next, go to the Relaying tab and configure allowed relay hosts. For my setup I went to the Host-based relay section and added each individual host that I want to have use my UTM for e-mail relaying.

Lastly, you must configure your UTM to send e-mails out to your ISP’s mail relay since by default the UTM tries to send e-mails out itself on port 25, which in my case is blocked. Do this by going to the Advanced tab and scrolling down to smart host settings. Configure the mail relay server, credentials, and port required there.

That part was fairly straightforward; however the spam protection feature of the UTM was preventing any messages sent to the UTM from being sent to the internet.

After much weeping, wailing and gnashing of teeth (including adding an SPF record for my domain) I discovered that the solution was to ensure that outgoing mail shows the node’s name in the From: field. If your server’s name is server, the from should always be server@yourdomain.org. I haven’t dug into why, but oh well! It works.