DerLinkman Check if you have a entry called search within the /etc/resolv.conf file.
Probably not everybody is happy (or can use) with this workaround:
Googled (but known):
"From man resolv.conf:
The search list is normally determined from the local domain name; by default, it contains only the local domain name. This may be changed by listing the desired domain search path following the search keyword with spaces or tabs separating the names. Resolver queries having fewer than ndots dots (default is 1) in them will be attempted using each component of the search path in turn until a match is found. For environments with multiple subdomains please read options ndots:n below to avoid man-in-the-middle attacks and unnecessary traffic for the root-dns-servers. Note that this process may be slow and will generate a lot of network traffic if the servers for the listed domains are not local, and that queries will time out if no server is available for one of the domains.
The search list is currently limited to six domains with a total of 256 characters."
This is helpful if you are part of a LAN environment that has its own DNS server so that people can type simple names to reach local resources. If you don’t have a home or corporate LAN with your own DNS server it’s nothing you really have to worry about.
I assume, in companies there are a number of mailcows in use with own DNS servers. In future IMVHO this should be fixed in a proper/better way.