Can't send emails from Thunderbird

My friend has a problem with his Thunderbird client. He is able to receive emails just fine but
can't send any emails. Every time he tries he gets this error.

Sending of the message failed.
The message could not be sent because the connection to Outgoing server (SMTP)
timed out. Try again.

I just installed Thunderbird on my PC and connected to the same network and have the same problem. I am using different email service but get the error too.

I have tried playing with the different protocols but nothing seems to help.

Most likely direct smtp is blocked by his ISP. (many ISPs and larger networks block port 25 to stop spam).
You should try submission instead. Port 587

He is actually using port 587 but still can't send emails.

ok... is the url to the mailserver correct? does the mail provider use different machines for processing incoming and outgoing mail?

Did you choose starttls encryption in firefox and the mailserver does not offer it? or vice versa (e.g. mailserver enforcing starttls but you did not coose it)?

Can you somehow (nmap) make shure the needed ports are accessible?

URL should be and he uses no encryption at all.

I have no clue about the other stuff.

Can you troubleshoot with something else? Opera has a built in mail client you could try it with that.

Ok.. I scanned The following ports are open:

Scanning ( [1000 ports]
Discovered open port 25/tcp on
Discovered open port 110/tcp on
Discovered open port 995/tcp on
Discovered open port 143/tcp on

So they offer smpt (25), pop3 (110), imap (143) and pop3s (995) which leads to 25 beeing the only avaliable port for sending mail.

Intense scna of all ports still pending... so I hope the ISP your fiend uses does not block port 25 ^^

This is strange. He said that before it was on Port 25 and it didn't work. Now i have changed the port to 25 and it worked. I think it has something to do with the ISP because he has 2 different lines in his home and on one the Thunderbird is able to send the emails and on the other line it can't.

Lines.. you mean IPS? Well if the provider of one of the lines descided to not allow his clients to send mails directly using port 25 to fight spam from personal computers its clear he cant connect.

I also never allow traffic from 25 outwards on networks I manage. I think the mail provider does no good job to be honest.