Cannot save email domain

ERPNext
1

Unable to save my email domain on a particular ERPNext instance. Throws the following error:

Traceback (most recent call last):
  File "/home/frappe/frappe-bench/apps/frappe/frappe/email/doctype/email_domain/email_domain.py", line 62, in validate
    sess = smtplib.SMTP(cstr(self.smtp_server or ""), cint(self.smtp_port) or None)
  File "/usr/lib64/python3.6/smtplib.py", line 261, in __init__
    fqdn = socket.getfqdn()
  File "/usr/lib64/python3.6/socket.py", line 673, in getfqdn
    hostname, aliases, ipaddrs = gethostbyaddr(name)
UnicodeError: encoding with 'idna' codec failed (UnicodeError: label too long)

The same domain gets saved on another server without any issue.
Please guide.

2

My server’s hostname exceeded 64 characters. And hence it kept failing.
More on the issue here: Issue 32958: socket module calls with long host names can fail with idna codec error - Python tracker

I changed the hostname of the server to a smaller string and it worked fine.