[stunnel-users] Sending Email from PLC Without Authentication with gmail

Stephen Gates sgates at hkscholz.com
Thu Jun 27 15:07:52 CEST 2013

"The issue with your situation is not stunnel but the fact that your SMTP
client does not have the capability to provide authentication. 

As you mentioned, Gmail will require authentication information from the

If that information is not provided by the SMTP client application, then the
SMTP transaction will fail.


I would suggest you consider setting up some kind of SMTP Relay. Which will
serve as a proxy between your PLC and Google SMTP servers. 


You can also take a look at this document and if possible implement the last



Thanks for your help Leandro. Do you have a suggestion for a SMTP Relay?? I
have tried Free SMTP Server which was the only thing that has worked so far
and  worked almost perfectly except that it can only send out 10 emails a
day. And I need more capacity for sending than that.


I also have used trial versions of ArgoSoft, 1st Mail Server and QK SMTP
Server but couldn't get those to work.


I have tried the Google suggestion for using asmpx.l.google.com but I need
to send to vtext.com addresses which are outside of the google domain. I
tried adding the vtext.com addresses to googlegroups.com and sending emails
using the asmpx.l.google.com server but vtext did not receive the emails for
googlegroups.com. So I'm desperate to find some sort of solution.




Stephen Gates

Harold K. Scholz Company

7800 Serum Avenue

Ralston, NE  68127



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