# Thunderbird and dns lookup failure for an IMAP server

## toralf

I've here a user-mode-linux image attached with a static ip address 192.168.1.50 to my host over a tap device and a bridge. All network connections to that system are fine, name resolution works too, tested with commands host, dig and ping. Both at host and at the UML image I' running dnsmasq.

But Thunderbird 10.0.4 is not able to access an IMAP server at the UML via the given hostname, only via the given ip address. The entries in the hosts tables are made both at server and at UML.

 :Sad: 

----------

## Hu

Could you clarify what machines are running the various programs? *toralf wrote:*   

> Thunderbird 10.0.4 is not able to access an IMAP server at the UML

 Does this mean that the UML is running a Thunderbird which attempts to connect to an IMAP server on the Internet, that the UML is running a Thunderbird which attempts to connect to an IMAP server on the host, or that the IMAP server is on the UML instance and a Thunderbird elsewhere attempts to contact the UML-hosted IMAP server?

When you ran the connectivity tests, did you run them as the same user that runs Thunderbird?  If you ran the connectivity tests as root, then permissions problems with resolver files would not affect the test tools, but could affect Thunderbird.

----------

## toralf

Thunderbird is my mail client at the host system. The UML is used to run the courier server. The network check were run both as user (which runs thunderbird) and as root. I tseems that Thunderbird uses its own name resolving libs rather then those libs which are used by host, dig and ping.

----------

## pilla

Moved from Kernel & Hardware to Networking & Security.

----------

