Postfix SMTP banner show multiple hostnames
Solution 1:
You need to edit master.cf
replace the line starting with "smtp" with:
1.1.1.1:smtp inet n - - - - smtpd -o myhostname=mail.domain1.com
2.2.2.2:smtp inet n - - - - smtpd -o myhostname=mail.domain2.com
If you set one variable multiple times only one of them will remain.