SMTP: The input appears to be a DNS hostname but cannot match TLD against
9 days later
KevinTheJedi 
Sorry, have been away.
- Edited
This error stems from laminas/laminas-validator:src/Hostname.php#L76. But this packages seems to include de as a valid TLD so I don't know what's going on here.
Cheers.
KevinTheJedi
Good idea. With IP the error message changes to:
cannot connect to host; error = stream_socket_client(): Unable to connect to ssl://81.169.145.133:465 (Unknown error) (errno = 0 )
KevinTheJedi
the "de" seemS not to be the problem. I just checked another hostname "smtp.t-online.de". If i do so, I don't get the TLD check error.
Then it sounds like either something on the webserver is blocking the request or something on the mail server is blocking it.
Cheers.
For a blocked request it don't seem to be the right error message.
- Edited
I’m talking about the IP Address. Idk what’s going on with the hostname as that doesn’t make any sense looking at the code.
Did you copy the hostname from somewhere by chance? If so, maybe it has a hidden character or something that’s throwing it off? Maybe try typing the hostname out. I’m really just spitballing here as the other .de hostname worked fine.
Cheers.
a year later
Hei, I know this post is kinda old, but I got the same problem.
I can't find anything related to this error...
I host it on Strato Webspace, but when I host it on my own Strato Webserver it works perfect.
Is Strato maybe blocking something?