smtp.de.opalstack.com timing out

kylotan

I can't send any email because Thunderbird tells me that smtp.de.opalstack.com is timing out. Can someone look into this please?

kylotan

Seems to have resolved itself now...

sean

Sorry about this, there was a brute force attack happening on the SMTP service.

We've blocked the attack so you should be able to connect now.

dragonxi

Which kind of solution could opalstack provide so that the opalstack server would autonomously detect and solve attacks against mail.de.opalstack.com ?

Our feedback:
(1)
The same timing problem has occured many times to those of our guys who have tried to setup email for mail.de.opalstack.com. Problem has been temporary avoided by configurating with mail.us.opalstack.com.
(2)
The problem has been discovered by using not only Thunderbird client but also other open source email clients - and both in LAN workstations and with mobile smartphones.
(3)
All of our emails use POP.
(4)
No timing problems with mail.us.opalstack.com

sean

dragonxi we're presently working on integrating fail2ban with Postfix on the SMTP servers. When that's done these attacks will be handled automatically.

sean

dragonxi sorry, I just noticed that you said mail.de.opalstack.com, not smtp.de.opalstack.com (which is the subject of this forum post).

There have been no attacks on mail.de.opalstack.com.

The next time you notice this problem, please email Opalstack support (not a forum post) with the following info:

The precise date and time (with time zone) that you noticed the problem.
The name of the mail user that you are trying to set up as an account in your mail client.
The public IP address of the system that you are running the mail client on (ie the address that you get at whatismyip.com)
A screenshot of your mail settings
A screenshot of the error message

Once you've emailed the info to support we'll look into it further.

kylotan

smtp.de.opalstack.com is timing out again...

sean

kylotan we're not seeing any problems on smtp.de.opalstack.com from our end at this time.

If your SMTP connection is timing out then please email support to let us know your mail user name and client IP address and we'll then look into it further.

kylotan

sean It fixed itself within the hour. But it's not helpful to ask us to email you when the email is down...

sean

kylotan It fixed itself within the hour.

if it fixed itself within an hour, then it was possibly an IP block due to failed logins.

kylotan But it's not helpful to ask us to email you when the email is down...

That's a great point! In these cases you can also reach us via:

The help widget that appears in the lower-right corner of the dashboard
The contact form at https://help.opalstack.com/contact
If you're on Twitter, you can send a DM to @opalstack.
If you have an externally hosted email account, then you can add that to your account contact info and then contact us via email from that address.

kylotan

sean if it fixed itself within an hour, then it was possibly an IP block due to failed logins.

It's unlikely to have been failed logins from our end because the auth details are all stored in Thunderbird and wouldn't have changed in months. If it's blocking based on an address range rather than a single IP, please make it more specific or more lenient, because probably almost half the UK is on the same ISP as me.

houdinihound

kylotan I'd imagine it's also possible that a bot was trying to brute force the SMTP server having stumbled (guessed or local malware perhaps?) onto your mail account name. I'd email the support guys with the time and the mail account(s) experiencing the problem and ask him check the logs for suspicious activity.

HTH.