I have a mail server which received emails from our company PDAs and dumps them to a drop box (anything to another domain is reject) which has been working for a number of years.
However we are now getting more and more phones which are unable to send emails to this drop box - looking at the logs it appears that T-Mobile now give each phone it's own IP address and hostname (previously there was a pool of about 5 which were used) - for example whenever the phone fails to send a message like the following appears in the log
May 16 13:49:37 photo postfix/smtpd: warning: 220.127.116.11: hostname customer35650.97.ld.cust.t-mobile.co.uk verification failed: Host not found
Looking at all the failures it appears that T-Mobile haven't set up reverse DNS entries as nslookup says
** server can't find customer44546.104.wv.cust.t-mobile.co.uk: NXDOMAIN
Connecting to WiFi at home or work (no VPN off site) and attempting to send shows that the sending from the device works.
Is it possible to disable the name checks in Postfix?