Port 25 is blocked on nbn connection with static ip but not 4g back up with no static ip

[Char8]

Hi 

I have a monitoring program that sends me emails on alarms. Since I have connected to the nbn with the static ip it will not foward emails through port 25.  Im 95% sure when I was using the 4g backup with no static ip it worked with port 25.  Does this make sence?

[cf4]

It makes sense that port 25 is blocked. The port is blocked by most ISPs to prevent spamming. Suggest you try using another port for forwarding emails.

[Char8]

So port 25 works when its in 4g back up mode?  So do I have to open a port through the modem or do telstra have others. I dont know alot.  Cheers

[cf4]

Port is not blocked by modem but by the network. Port 25 is the only port I know off that is blocked. 

[Char8]

Ok 

I have tried other ports. They dont work maybe I'm not setting them up correctly? Everything runs fine on 4g backup.

[Mkrtich]

Hi - could you elaborate of how the alarm equipment generates the email to your address - do you have an embedded controller capable of sending a direct outgoing email to your external email address using Outgoing Server SMTP on Port 25 or does it send an email message to a PC on your network which then forwards that email to your personal address - wasn't sure if your first post used the word 'forward' literally.  

How often does the alarm/monitoring equipment do this routine and send an update - on an event or every x minutes 24/7. Is the monitoring equipment on site or external to premises - wondering if there is a Firewall or NAT Loopback issue? What modem model and firmware are you using? 

Can a separate device with email configured as POP3/SMTP send emails successfully from the site where the monitoring equipment is located and are you receiving emails from other people who use POP3/SMTP instead of IMAP?

[Reggie4806]

Sounds like your program is acting as an SMTP server delivering messages directly to recipient servers. From memory outbound connections to port 25 are blocked unless you purchase static IP or a business service (includes static IP). Are you sure you have static IP?

Can you tell your program to relay via mail.bigpond.com as the outgoing (SMTP) server? No authentication is required when you are on a Telstra connection.

Or use a third party mail service with an SSL/TLS enabled outbound server (eg gmail). These typically use port 465 or 587 which are not blocked, but will require you to login with an account.