Fix EHLO for multi-front platform

First verify that the VIP used for outgoing traffic has a correct reverse DNS record:

host 195.54.62.XX

Fix it if necessary. Next, change the /etc/mailname on every VM. Value should be strictly identical to the reverse.

Last step, indicate to every MTA’s VM to use a custom EHLO value instead of the hostname. For exim simple create a file /etc/exim4/exim4.conf.localmacros with the following content:

REMOTE_SMTP_HELO_DATA=<reverse_value>