Strange mixture of IPv6 and IPv4 for SMTP

Crashing eM Client
1

I cannot send any e-mail.

I’m on a public IPv6 connection.
My mail server is reachable via both IPv6 and IPv4.

Both resolve for my server:
(I’m masking all ip adresses partially for privacy reasons)

Non-authoritative answer:
Addresses: 2a01:4f8:xxx:yyy::2
144.76.ggg.hhh

From the emClient log, it seems it uses a strange mixture:

[SMTP] MailClient.Accounts.SocketException: Connection failed due to the following reason:
“A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. [::ffff:144.76.ggg.hhh]:25”

Webdav and IMAP connections to the same server work.

2

@Gary This seems like a pretty obvious bug to me. Any hints how to fix this? Can I force eMClient to use IPv4?

3

As long as your IP and DNS is valid I wouldn’t think it would make any difference when sending mail using either a IPV6 or IPV4 connection.

You can have issues if the eg: SMTP Server Settings “are incorrect in the mail client” or “the SMTP port is blocked” in some way.

So update what your eM Client “SMTP server address” , “Server Port” and “Security policy” are, so we can check those. Also what SMTP mail server do you send through.

Next if you are running any eg: Optionally installed Firewall / Security program, or Optionally installed Antivirus programs or VPN, try completely disabling those to test incase of interference.

4

Thanks a lot for the hints!

It seems my ISP blocks outgoing port 25, and all my other mail clients selected a different SMTP port.

5

It seems my ISP blocks outgoing port 25

If you are using POP account for sending and Port 25 is blocked, you can alt use the secure SMTP ports 465 or 587 as per @Gary advised below in another thread.

The port and security policy combinations are very specific:

SMTP
Port 587 = Force usage of SSL/TLS
Port 465 = Use SSL/TLS on special port (legacy)
Port 25 = Use SSL/TLS if available