SMTP Diagnostics 1.8.0.74 could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this software available.
This PC program was developed to work on Windows XP, Windows Vista, Windows 7, Windows 8, Windows 10 or Windows 11 and is compatible with 32-bit systems. The program's installer files are commonly found as sdcmd.exe or SMTPDiag.exe etc. This software is a product of White Peak Software Inc.
The following version: 1.8 is the most frequently downloaded one by the program users. We cannot guarantee that the program is safe to download as it will be downloaded from the developer's website. Before launching the program, check it with any free antivirus software. The program lies within Communication Tools, more precisely E-mail Tools.
From the developer:
SMTP Diagnostics is a program that assists with troubleshooting problems that can occur with outgoing mail (SMTP). You can send a test message, with or without attachment(s), and view the protocol messages exchanged between your computer and the mail server. This information can help you analyze problems or can be passed on to technical support personnel.
You may want to check out more software, such as Free SMTP Server, Advanced SMTP Server or Synametrics Smtp Gateway, which might be related to SMTP Diagnostics.