Android Question mtp connection is closed

[Robert Valentino]

When user using my App to send me a support request Email (I am using SMTP) the user reported that he gets the message: mtp connection is closed

What does this mean? And how can I fix it?

Thanks

BobVal

 

[Erel]

I guess that the correct message is: smtp connection is closed. There is no "mtp connection" in smtp.

Are you using your own mailbox account to send the messages or the user's mailbox?

 

[Robert Valentino]

Yes. I am using an account I have and this seems to work on every other device just not this users.

 

[Erel]

It is possible that the network firewall blocks the outgoing request. Which port are you using? Port 25 can be problematic.

 

[Robert Valentino]

I am not sure why but I am using port 587, has always worked in the past