Diagnostics

The diagnostics page provides a number of key pieces of information about SmarterMail that are important for system administrators. It's also important for SmarterTools support as information on this page can be helpful when troubleshooting issues. The page is broken out into various cards, as described below.

Product Information

This card has information about the version of SmarterMail that is currently installed, including:

• Version - The licensed edition of this installation: Free, Professional, or Enterprise. This simply reflects which edition your license key activates — it doesn't indicate whether the license itself is currently validating successfully; that's what the Product Activation field below is for. If you've recently upgraded or downgraded your license (for example, from Professional to Enterprise to gain access to features like SmarterMail Mobile push or clustering), this field is a quick way to confirm the new edition took effect after the license was applied.
• Build - The exact build number installed, along with the date that build was released, e.g. 100.0.0.12345 (5/1/2026). SmarterTools support will often ask for this value first when troubleshooting, since it tells them exactly which codebase — and which bug fixes or regressions — apply to your installation.
• Product Activation - Whether the installed license is currently validating against SmarterTools' licensing servers. A Passed status means the license validated correctly. A Failed status means SmarterMail could not confirm the license is valid, and it has real, immediate consequences: users are blocked from logging into the web-based Webmail interface entirely until the license validates again (IMAP, POP, SMTP, and other protocol logins are not affected by this particular check, but the primary way most users and administrators access their mailboxes is). If you see a Failed status, check that the server has outbound internet access (see the Internet Connectivity card below) and that the license key entered under Settings > Licensing hasn't expired or been revoked. On the Free edition, this field always reads Does not apply to Free Edition, since the Free edition doesn't require activation against a paid license.

System Settings

This card details information about the system SmarterMail is running on, including:

• SDK Version - The specific .NET runtime SmarterMail is currently executing under, e.g. .NET 8.0.7. Despite the name, this is not the legacy .NET Framework — current versions of SmarterMail run on modern, cross-platform .NET (the same runtime family used on both Windows and Linux installations), and this field simply reports whichever specific runtime version is installed on the server. If SmarterTools support asks you to update your server's .NET runtime as part of troubleshooting or before upgrading SmarterMail, this is the value they're referring to, and it's the fastest way to confirm the update actually took effect after you install it.
• OS Locale - The locale (language/region) that the operating system itself is installed with, e.g. en-US - English (United States) or de-DE - German (Germany). This is the OS's installed UI culture, not a per-user or per-domain language setting inside SmarterMail.
• OS Date Format - The short date format the operating system's locale applies, e.g. 7/15/2026 for en-US versus 15/07/2026 for a UK or European locale. (I.e., mm/dd/yyyy or dd/mm/yyyy, etc.)
• OS Time Format - The short time format the operating system's locale applies, e.g. 2:30 PM for a 12-hour locale versus 14:30 for a locale that defaults to 24-hour time.
• OS Default Encoding - The default text encoding the operating system falls back to when one isn't explicitly specified, e.g. Unicode (UTF-8), utf-8. On Linux installations this is always UTF-8. On Windows, however, it reflects the server's configured ANSI code page, which is tied to the OS locale — a US-English Windows server typically reports something in the Windows-1252 family, while a Windows server installed with a Japanese, Chinese, Cyrillic, or other non-Western locale reports a different code page entirely (and only falls back to UTF-8 if that code page can't be resolved).
• OS Time Zone - The time zone set for the operating system, e.g. (UTC-06:00) Central Time (US & Canada).
• OS Version - The operating system that SmarterMail is running on, e.g. Microsoft Windows 10.0.20348 on Windows Server 2022, or a kernel string such as Linux 5.15.0-91-generic on Ubuntu.

These fields matter most when something environment-specific is producing unexpected behavior rather than an outright error. For example, if a Windows-based SmarterMail server was provisioned with a non-English regional locale by mistake, OS Default Encoding might report a non-UTF-8 code page instead of UTF-8. In that situation, certain non-ASCII characters in message headers, log entries, or generated reports that assume UTF-8 could render as garbled or mismatched characters, even though nothing in SmarterMail's own configuration looks wrong. Similarly, if support asks you to compare timestamps between a log file and a report and the numbers don't seem to line up, check OS Date Format and OS Time Zone first — a server running in a dd/mm/yyyy locale can make a date like 3/4/2026 easy to misread as March 4th when it's actually April 3rd, and a time zone mismatch between the server and the administrator reviewing the logs can make events appear hours apart when they actually happened at the same moment.

Folder Permissions

SmarterMail requires certain permissions to be applied to folders so it will run properly.

• Permissions Check - SmarterMail verifies this by writing a small, temporary test file into the App_Data folder inside its own installation directory, then immediately trying to delete that same file. If both the write and the delete succeed, this shows Passed; if either operation fails, it shows Failed. A Failed result almost always means the account SmarterMail's service is running as doesn't have full read/write/modify permissions on the installation directory (or on the specific drive/volume it lives on) — this can happen after an OS-level permissions change, a migration to a new drive or volume, a restrictive antivirus/EDR policy, or (on Linux) an ownership mismatch between the SmarterMail service user and the installation folder. To resolve it, confirm which account the SmarterMail service is running under and grant that account full read/write/delete permissions on the SmarterMail installation folder (and its App_Data subfolder specifically), then re-run the Diagnostics page to confirm the check now passes.

Internet Connectivity

SmarterMail generally requires access to the internet in order to run properly. There are some instances where it's used in "air-gapped" networks, or behind restrictive network firewalls. In these cases, several checks on this card will fail even though SmarterMail's core mail functions (SMTP, IMAP, POP, etc.) will perform just fine. This card runs six specific checks and reports Passed or Failed for each:

• Yahoo Resolve Check and Google Resolve Check - Confirm the server's DNS resolver can resolve a public hostname (www.yahoo.com and www.google.com, respectively) to an IP address. These verify that basic outbound DNS resolution is working at all, independent of any specific SmarterTools service.
• Yahoo HTTPS Check and Google HTTPS Check - After resolving the hostname, SmarterMail attempts an actual outbound HTTPS request to that site. These confirm that outbound port 443 traffic isn't being blocked by a local firewall, proxy, or network policy, again independent of SmarterTools.
• Echo Check A0 and Echo Check A1 - These are the checks that matter most for SmarterMail itself: they send an outbound HTTPS request specifically to SmarterTools' own activation/licensing servers (a0.smartertools.com and a1.smartertools.com) and confirm the expected response comes back. These are the actual endpoints SmarterMail depends on for license activation and validation checks, so a failure here is the one most likely to explain a Failed Product Activation status on the card above.

If your server is intentionally air-gapped, or sits behind a firewall that only permits outbound traffic to a specific allow-list, it's normal and expected for some or all of these checks to fail — that's not a bug, it's the firewall doing its job. The important distinction for an administrator to make is between an expected failure and an unexpected one. For example, if your organization's policy deliberately blocks all outbound HTTPS traffic except to a small set of approved destinations, seeing all six checks fail is expected, and you'd simply accept that license activation/update checks won't succeed automatically (some SmarterMail deployments handle this with an offline or manually-applied license). On the other hand, if a firewall rule was supposed to allow outbound HTTPS only to smartertools.com but was misconfigured and is instead blocking all outbound traffic on port 443 (or blocking DNS resolution generally), you might not notice the impact right away since inbound/outbound mail flow uses different ports (25, 587, 993, etc.) — but that same misconfiguration could also be silently blocking things like RBL/URIBL lookups, antispam and antivirus definition updates, or Let's Encrypt certificate renewal, all of which also depend on outbound internet access. Use this card as a quick way to confirm which category you're in before assuming a failure here is harmless.

Top Log Files by Size

Keeping tabs on log files is important for a system administrator. The larger the log file, the longer some reports can take to process. In addition, logs can grow in size depending on the log level set. Large logs, obviously, take up space on a mail server, so being able to see how large some logs get can help an administrator reduce the amount of space needed, or, conversely, add disks (or disk space) to increase space available. This card scans the server's configured log folder (the Log Files path set under Settings > General Settings > Paths) for the ten largest .log and .zip files it finds, and lists them by overall size in descending order.

For example, if an administrator temporarily raises the SMTP-In log to Trace level while troubleshooting a delivery issue and then forgets to set it back to Information afterward, that log can silently balloon to several gigabytes over the following days or weeks as every low-level protocol event gets recorded. This card surfaces that immediately — the oversized SMTP-In log will appear at or near the top of the list — so the administrator can lower the log level back down and clean up or compress the existing file before it consumes enough disk space to cause a real problem, such as the spool running out of room to accept new mail.

Loaded JSON Files Over 15MB

SmarterMail stores a large portion of its configuration and per-account data — domain settings, user settings, greylisting filters, and similar data — as JSON files on disk, and it reads those files into memory (from disk, or from an internal cache) whenever it needs them. Whenever the underlying file-loading routine reads one of these JSON files from disk and finds it's larger than 15MB, it logs a performance warning and flags that file so it shows up here; the flag clears automatically if the file later shrinks back under 15MB. This card lists the twenty largest flagged files, sorted by size, and clicking View JSON Files opens a dialog showing the full file path and exact size (in bytes) of each one.

A JSON file this large is usually a symptom of something that's grown unbounded over time rather than a normal configuration file — for example, a domain's alias list, an individual user's settings file, or a greylisting/filter data file that's accumulated years of entries without ever being pruned. Because these files can be read into memory in full rather than streamed, an oversized file takes measurably longer to load and parse each time it's needed, and can noticeably increase memory usage for that operation. If you see an entry here, open the file path shown in the dialog to identify which domain or user it belongs to, and review whether old or unused entries in that file (aliases, filter rules, historical settings, etc.) can be cleaned up to bring it back under the threshold.