dn: uid=alise,ou=peoples,dc=acme,dc=com
objectClass: inetOrgPerson
objectClass: top
cn: alise
sn: alise
uid: alise
userPassword: {SCHEME}password
mail: alise@domain1.tld
mail: alise@domain2.tld
mailAlias: bill@domain1.tld
mailAlias: bill@domain2.tld

ldapsearch -xLLL -b ou=peoples,dc=withsound,dc=ru '(mailAlias=bill@domain1.tld)' mail

dn: uid=alise,ou=peoples,dc=acme,dc=com
mail: alise@domain1.tld
mail: alise@domain2.tld

ldapsearch -xLLL -b ou=peoples,dc=withsound,dc=ru '(mailAlias=bill@domain1.tld)' mail=*domain1.tld


dn: uid=alise,ou=peoples,dc=acme,dc=com
mail: alise@domain1.tld