First, hi to all, i'm new here and i appreciate all the help that you can give me. Thanks in advance. I have a Server with 4GB RAM running Postfix 2.9.6 with Amavisd-new (ClamAV and SpamAssassin included) to filter the mail and signing it with OpenDKIM 2.6.8. I'm using SwiftMailer to deliver mail to Postfix via SMTP but I'm only able to send about ~2000 emails/hour. I think this is very low for postfix. The server is used for email marketing and that's why the added all filter and signing services. What I've read so far: - Postfix Tunning README - Postfix Bottle Neck Analisys - The Book of Postfix (chapter 22) We're also using a local DNS forwarder (dnsmasq). But we're still scratching our heads as to where to look for the bottleneck. Some configurations i'm using in main.cf: default_process_limit = 200 qmgr_message_active_limit = 50000 qmgr_message_recipient_limit = 50000 qmgr_message_recipient_minimum = 500 default_recipient_limit = 50000 minimal_backoff_time = 300s maximal_backoff_time = 900s maximal_queue_lifetime = 1d queue_run_delay = 5m bounce_queue_lifetime = 1d smtp_helo_timeout = 60s smtp_connect_timeout = 30s initial_destination_concurrency = 50 default_destination_concurrency_limit = 100 Does anyone have some idea what can i do? I forget something? I'll appreciate any advice. Thank you.