I have posted a question recently about sendmail not resolving host names. It looks to me as if it is failing to do AAAA lookups. Is is possible to prevent sendmail from trying to do AAAA lookups? This might solve the problem. I'm not very keen on recompiling sendmail - I'd like to keep the original (debian 3.0) binary for ease of upgrading!! I haven't managed to find answers on google groups.