SMTP Monitoring with NodePing

2023/08/22 by Leave a comment

In the world of email communication, Simple Mail Transfer Protocol (SMTP) plays a crucial role in ensuring the seamless delivery of messages. However, like any other technology, SMTP is not immune to issues that can disrupt email flow and affect business operations. To maintain a healthy and reliable email infrastructure, it is essential to monitor SMTP servers continuously. In this blog post, we will explore how NodePing can be used to monitor for SMTP functionality, packet loss, blacklisting, deferred queues, and MX/SPF records.

NodePing is a versatile and powerful server monitoring service that allows businesses to monitor their infrastructure’s performance and uptime. With its extensive range of monitoring checks, NodePing provides an excellent solution for monitoring SMTP servers and ensuring they are operating optimally.

Monitoring SMTP Functionality

Verifying the functionality of your incoming SMTP server is crucial to ensure that it can receive emails without any hiccups. NodePing’s SMTP check allows you to periodically test your SMTP server by trying to send a test email to a designated email address. If the test email is accepted, it indicates that your SMTP server is functioning correctly. In case of failures, like timeouts or server errors, NodePing will promptly alert you, enabling you to troubleshoot and rectify the issues.

Monitoring Packet Loss

Packet loss can severely impact the performance of your SMTP server and lead to email delivery delays or failures. NodePing’s ICMP PING check is a valuable tool to monitor packet loss and routing issues to to your SMTP server. By regularly performing ping tests, you can assess packet loss trends and determine whether network-related issues are affecting your email delivery. If a failure is seen, NodePing automated diagnostics will send you MTR results so you can quickly troubleshoot where the issue originates. Addressing packet loss problems promptly will lead to a smoother email experience for your users.

Monitoring SMTP Blacklisting

Blacklisting can be detrimental to email delivery, as it prevents messages from reaching their intended recipients. NodePing’s RBL check allows you to monitor your SMTP server’s IP addresses against popular DNS-based blacklists (RBLs) such as Spamhaus and Barracuda. By configuring blacklisting checks at regular intervals, you can quickly identify if your server’s IP addresses have been blacklisted, enabling you to take immediate action to resolve the issue and maintain a good sender reputation.

Monitoring Deferred Queues

When your SMTP server is unable to deliver emails to the recipient’s mailbox immediately, it sits in the deferred queue. If emails in your deferred queues are piling up, you likely have a delivery issue. NodePing’s PUSH check can watch your deferred queues and send you notifications if they rise above what you’re comfortable with; allowing you to investigate and resolve the underlying problems before they escalate.

Monitoring MX Records

MX (Mail Exchange) DNS records play a crucial role in email delivery by specifying the mail servers responsible for receiving emails for a domain. NodePing’s DNS check allows you to monitor the MX records of your domain to ensure they are correctly configured and that your DNS servers are responding with those records properly. Regular checks of MX records help you keep incoming mail flowing.

Monitoring SPF Record

Your SPF record is actually a TXT DNS record that specifies which servers are allowed to send email from your domain. If that record is missing, compromised, or your DNS servers aren’t responding, sending email may be blocked or delayed. NodePing’s DNS check will make sure your SPF record is available and hasn’t been hacked. That will keep your outgoing mail flowing.

In conclusion, email monitoring is essential to ensure the reliability and efficiency of your message communications. NodePing provides a comprehensive suite of checks that empower you to monitor for blacklisting, SMTP functionality, packet loss, deferred queues, along with MX and SPF records. By leveraging NodePing’s monitoring capabilities, you can proactively identify and address issues affecting your SMTP server’s availability and performance, leading to better email deliverability and improved customer satisfaction.

Remember, a robust email infrastructure is the backbone of modern businesses, and investing in reliable monitoring tools like NodePing with automated diagnostics is a step towards a smoother and more efficient communication system.

Start monitoring your SMTP servers with NodePing today by signing up for our free, 15-day trial and stay one step ahead of any potential email delivery challenges!

Filed under DNS, Email, Monitoring, PING, SMTP, uptime Tagged with , , , , , , , , , ,

Finding the Best Server Providers

2023/08/01 by Leave a comment

Great services need great boxes to run on. How do we know if a server or VPS host is performant and reliable?

We use dozens of different hosts for NodePing and our standards for performance and reliability are really high. There are many SaaS out there that host only on AWS. Putting all your eggs in one basket is nice for billing but would make our service fragile and vendor-dependent. We spread our boxes around to make it resilient and better represent the Internet’s disperate architecture for monitoring.

We have to take new boxes out and put them through their paces; kick the tires and make sure they’re solid. This is how we test out a new provider before we use a dedicated server or VPS.

Blacklisted

As soon as we have our IP assignments from the provider, we check to make sure the IPs aren’t listed in any spam blacklists using NodePing RBL checks. Most of our hosts don’t send any actual email but our public probes do a lot of SMTP connections to ensure our customers’ mail servers are functioning properly. If the IPs are blacklisted, we’ll need a clean IP from the provider or cancel and look elsewhere.

We’ll leave this RBL check running once an hour to make sure it doesn’t get listed half way through our testing period.

Blacklisted IPs can be a good indicator of provider quality even if the server won’t be sending any email. A provider that can’t keep spammers out of their service is unlikely to be able to keep a reliable network.

Incoming Traffic

Solid networks can be hard to find. We test for inbound packet-loss and routing issues using NodePing PING checks. We’ll sometimes test from a few different geographical regions to ensure global routing is stable. Anything less than 100% uptime for 30 days is unacceptable for us. If the provider had announced planned maintenance well in advance, we’d use NodePing’s maintenance feature to ensure the uptime stats remained accurate despite planned outages. In our decade-plus experience, a network that sees even one episode of packet-loss or route failure is going to continue to see them and isn’t stable enough for our use.

We’ll do the same for IPv6 addresses as routing and packet-loss can be independent of the IPv4 stack. Some providers have a hard time keeping their IPv6 blocks broadcasted and we’ve seen IPv6 completely fail while IPv4 continued to function normally.

We enable automated diagnostics for all our PING checks so we can see where on the route the packet-loss or routing failure is happening. Getting immediate MTRs can show us the weak links in a network and if we see issues with some of the usual suspects, we will for sure dump it. Yes, I’m looking at you, Cogent!

Outbound Traffic

Sometimes a network issue seems to only impact outbound routing. We use the AGENT functionality to assign additional PING checks to originate from the server being tested towards some of the other servers it would be connecting to if it’s moved into production. The AGENT software will run NodePing checks just like the public probes but originating from our test host. It’s a great way to detect outbound packet-loss and routing issues from the server. Again, anything less than 100% uptime on this test and the service isn’t going to make muster.

System Load

The performance of a VPS can be greatly impacted by issues outside our control. Two of the most frequent system load issues we’ve seen on VPS are noisy neighbors and host server backups.

A good provider won’t oversell their VPS host servers and will suspend anyone who is abusing more than their fair share of resources. If we end up on a box with noisy neighbors, the system load on our VPS will likely spike, starving our processes from getting the CPU, memory, networking, or storage I/O they need to function properly.

We’ve also come across providers where we saw system load rise every Saturday around midnight (GMT) for 30 mins or so. Turned out their backup process was overwhelming the disks and causing load issues on all the VPS on the host.

These types of issues are simple to find using PUSH checks that monitor the system load. Since we aren’t using these boxes for anything yet, we have to set the thresholds pretty low to detect load issues caused by resource starvation. This is one test that we’ll give a bit of slack to a provider if it fails though. Noisy neighbors or hungry backups can happen to any provider and we’ll give them a chance to find and address the cause. If it keeps happening though, pull the plug on that provider. It’ll just be worse once you start using the machine and an ongoing headache trying to get their support to do anything about it.

If a server can keep humming along for 30 days without any of the checks above failing, there’s a pretty good chance that provider and network are going to be solid and reliable. I hope this look into our vetting process will help you with your provider search for those elusive reliable networks and servers.

If you don’t yet use NodePing, please sign up for our free, 15-day trial and see for yourself how our monitoring can increase your uptime.

Filed under AGENT, diagnostics, Monitoring, MTR, NodePing, PING, PUSH, RBL, SMTP, System Monitoring, uptime Tagged with , , , , ,

Email monitoring done right

2013/02/25 by Leave a comment

For several years before starting NodePing I worked in a number of different roles in IT, including system administration, project management, infrastructure and network management, and development. A sizable chunk of that time was spent at an organization that ran email servers in a number of different countries scattered around the world. Making sure that all of those email systems were working properly and generating useful reporting was a huge challenge, and involved a lot of repetitive manual steps.

Availability report outputNodePing’s monitoring services were largely motivated by the desire to make widespread monitoring of web sites and other Internet accessible services as simple and automatic as possible. One of the reasons I’m so excited about our suite of email monitoring checks is that I know from personal experience how important these tools are, both from a sys admin’s point of view as well as from technical management roles.

The core of this set of tools is SMTP monitoring. This check has several options that allow you to check the remote SMTP server in a variety of ways. At its most basic, it can be used to check that the server is operating and answering to SMTP connections and is accessible. It can also watch the SSL/TLS certificates, and notify you in advance of when certificates will expire. The check also can be used to monitor if the SMTP server accepts or denies specific email addresses, which can be used for open relay monitoring. Authentication verification can make sure that the server is logging people in properly. This is particularly important when email servers are integrated with separate directory services, such as an LDAP service or Active Directory.

SMTP server monitoring should also be paired with RBL monitoring. This checks the server’s address against a number of different RBL services, and can notify you if the server has been blacklisted. Any experienced email administrator knows that staying off of these lists is critically important, and it is possible to get on a black list without doing anything outside of normal business practices. When it happens you need to know quickly so you can remedy or clarify the situation and get off of the black list before it negatively impacts business.

The IMAP and POP checks go hand in hand with the SMTP check to ensure that your customers and employees can retrieve mail from their inboxes. Like the SMTP check, these checks not only monitor that the server is accepting connections, but can verify authentication and warn you in advance if an SSL certificate is nearing expiration.

The final piece of the email service monitoring tool set is monitoring the web interface. Here NodePing’s HTTP Content check can be used to make sure that the service is responding with the proper web page, and the SSL check can verify that the web interface’s SSL certificate is in place and working properly, as well as warn of a nearing expiration date.

These checks together provide a full complement of tools for monitoring email services. For most systems, we’d suggest a full set of checks:

  • The SMTP service is operating properly on port 25, accept a STARTTLS command, accepts authentication, and accepts a given address for relay from an authenticated user. All of this, with verification of the TLS certificate, can be done with one check.
  • The SMTP service is listening and accepting SSL based connections on port 587.
  • The SMTP service rejects open relay requests.
  • The SMTP service accepts a local address from non-authenticated hosts.
  • The server is not on any RBL’s.
  • The IMAP server is operating properly on port 143 and authenticating properly
  • The IMAP server is operating properly on port 993 and the SSL certificate is good
  • The POP server is operating properly on port 110 and authenticating properly
  • The POP server is operating properly on port 995 and the SSL certificate is good
  • The web interface is operating properly on port 80 (if that is supported)
  • The web interface is operating properly on port 443 and the certificate is good.

This is a long way from a check that just monitors if a port is listening somewhere. It is the full set of checks that together help to ensure a healthy email system. We continue to extend our monitoring service and make our checks smarter, with the goal to take as much of the manual busy work out of the hands of busy administrators and allow them to focus on tasks that use their actual skills.

If you are responsible for email servers and haven’t added NodePing’s monitoring to your tool set yet, sign up for our free trial and give a try!

Filed under Email, POP, RBL, SMTP, SSL, Using NodePing Tagged with ,

RBL Monitoring

2013/01/15 by Leave a comment

What better way to top off our email monitoring enhancements than with a new check type! We’re happy to introduce our RBL check.

RBL, or DNSBL, stands for “Real-time Black List,” and is used to publish the addresses of computers or networks linked to spamming, malware, or other abuses which system administrators may want to block from accessing their networks.

There are hundreds of RBLs in existence, which use a wide array of criteria for listing and delisting of addresses. These may include listing the addresses of zombie computers or other machines being used to send spam, listing the addresses of ISPs who willingly host spammers, or listing addresses which have sent spam to a honeypot system.

If the IP addresses of your servers appear on these RBLs, there’s a good chance you’ll have difficulty interacting with networks that subscribe to these RBLs. For instance, if your SMTP server is listed, you’ll likely be unable to send email to the systems that use the RBL you are listed on.

You can use our new RBL check to ensure that your servers aren’t listed and to receive notifications if they do get listed, allowing you to quickly take steps to remove your addresses from those RBLs. You can find more details about which RBLs we check and how to set them up in our RBL Check documentation.

Adding RBL checking to our already robust email monitoring checks for SMTP, POP3, and IMAP4 will help you sleep at night knowing that email is flowing as it should be.

RBL monitoring checks are available to all NodePing accounts. If you don’t have an account yet, you can sign up for your free 15-day trial of our server monitoring service.

Filed under Email, Monitoring, NodePing Updates, RBL, SMTP Tagged with , , , ,

SMTP Check Enhancements

2013/01/02 by Leave a comment

We’ve rolled out some important enhancements to our SMTP check that will help ensure your email server is running as it should be.

Added enhancements include:

  • Non-standard ports
  • SSL/TLS support including certificate verification and expiration warning
  • STARTTLS support
  • AUTH with support for PLAIN, LOGIN, and CRAM-MD5
  • Mail acceptance verification including open relay notification

The SMTP check will now not only verify that your email server is running but can also optionally check to see if your server is an open relay or properly accepting mail for a particular email address.

The new open relay functionality will test to see if your mail server will accept mail for an address that should not be allowed. If your server is an open relay, we will send you a notification.

It’s also important to verify that your email server is not rejecting mail that it should be accepting. There are many reasons an SMTP server may reject email. The configuration may have changed or a particular mailbox may be over its quota. This enhancement verifies that your server will accept messages to an email address of your choice and send you a notification if it is rejected.

We’ve added extensive SSL/TLS support including STARTTLS as well as certificate verification and certificate expiration warnings. Simply set how many days in advance of the expiration you would like to be notified and we’ll send you an alert, giving you time to renew and install your new certificates.

The new optional AUTH support allows you to verify that users can log in and send mail using industry standard PLAIN, LOGIN, and CRAM-MD5 AUTH mechanisms.

You can find more information about our new SMTP check enhancements in our documentation.

These enhancements are available now to all NodePing customers. If you don’t currently have an account, please sign up for our free 15 day trial.

Filed under Monitoring, NodePing Updates, SMTP, SSL Tagged with , , , ,