Sometimes when I try to send a mail to microsoft domain address I can see in exim4 mainlog lines like this :
eur.olc.protection.outlook.com address already in use
After hours or days in the exim4 queue, the mail has sent and sometimes client didn't receive it.
And Sometimes when I try to send a mail to another domain like gmail.com I can see line like this :
address_mail_to R=dnslookup_users T=remote_smtp defer (-53): retry time not reached for any host
I have tried this solution quick fix it' works but the problem comes back again and again, I would like to fix this problem really