My Postfix system is reachable and everything is working (I set it up yesterday). But during multiple occasions today, it just wasn't reachable and I really don't know what to do. Usually it when not working it went that way: I tried logging into my Mail-Account on my phone after logging in on Mozilla Thunderbird on my Computer. Setting up the mail account on my phone just didn't seem to work. After trying to logging in on my phone the server (IMAP and SMTP) wasn't responding at all. I tried "contacting" it using telnet, but that didn't work. Then after waiting a few minutes, it just worked as if nothing happened.
One thing to note: Connections from the server (using roundcube) were always working.
I just can't figure out what's going on here and what could lead to the whole server not answering (the logs show nothing irregular).
Any help is appreciated :)
My main.cf is as follows:
smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU)
biff = no
# appending .domain is the MUA's job.
append_dot_mydomain = no
# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h
readme_directory = no
# See http://www.postfix.org/COMPATIBILITY_README.html -- default to 2 on
# fresh installs.
compatibility_level = 2
# TLS parameters
smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_security_level = may
smtp_tls_CApath=/etc/ssl/certs
smtp_tls_security_level = dane
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = example.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = $myhostname, , localhost
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_command = /usr/bin/procmail-wrapper -o -a $DOMAIN -d $LOGNAME
mailbox_size_limit = 0
recipient_delimiter = +
inet_protocols = all
virtual_alias_maps = hash:/etc/postfix/virtual
sender_bcc_maps = hash:/etc/postfix/bcc
sender_dependent_default_transport_maps = hash:/etc/postfix/dependent
home_mailbox = Maildir/
smtpd_sasl_auth_enable = yes
broken_sasl_auth_clients = yes
smtpd_recipient_restrictions = permit_mynetworks permit_sasl_authenticated reject_unauth_destination
smtp_dns_support_level = dnssec
smtp_host_lookup = dns
allow_percent_hack = no
tls_server_sni_maps = hash:/etc/postfix/sni_map
mynetworks_style = subnet
