Hi everyone,
I think I stumbled upon a problem with postfix 3.5.X and very long
header lines. To reproduce, I build a very simple setup with two VMs:
- "A" running postfix 3.3.0 (xubuntu 18.04 package)
- "B" running postfix 3.5.6 (xubuntu 20.10 package)
Both are relayhosts for each other and accept messages for their local
mailbox (A takes mail for intern01.local, B takes mail for
intern03.local). From my host, I transmit an email
(msg_longheader_3k.eml) for a@intern01.local to B and and for
a@intern03.local to A, which is then relayed to A and B, respectively.
Sending a long header line of 3000 bytes bytes to B and having it relay
to A, I end up with an incorrectly folded/chopped up header (see
attachment B2A) in the inbox. There is an additional line break after
the first line_length_limit (plus 4 for folding whitespace) bytes, which
marks the end of the header. The mail body then is filled up with the
remaining header bytes. Sending it in the other direction, using postfix
3.3.0 on A as relay, the message arrives intact and correctly folded
according to the setting of smtp_line_length_limit (see attachment A2B).
Additional observations:
- postfix 3.4.X behaves like postfix 3.3.X in this regard, the issue
does not occur there
- Sending the mail directly to a local mailbox, the message arrives
unchanged (neither chopped, nor folded).
- Increasing line_length_limit to some value larger than the length of
the header line prevents the described issue
- Increasing smtp_line_length_limit to a larger-than-header-line value
(but leave line_length_limit at 2048) does *not* prevent the issue;
instead, I get a single 2048-byte long line followed by two linebreaks
- It does not make a difference if TLS is used; I tried none/none
combinations for smtp(d)_tls_security_levels and
smtp_tls_security_level=encrypt on relay and
smtpd_tls_security_level=may on recipient.
Thus, I would suspect that there might be a problem in the code
responsible for reconstructing the chopped message within the smtp
module. Unfortunately, so far I haven't been able to put my finger on
the exact location.
Andreas
--- Begin Message ---
There is not much interesting stuff going on here.
Just some regular email plain text.
--- End Message ---
postconf -n
alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
append_dot_mydomain = no
biff = no
compatibility_level = 2
inet_interfaces = all
inet_protocols = all
mailbox_size_limit = 0
mydestination = $myhostname, AAAAA.AA, localhost
myhostname = mailserver.anwei.de
mynetworks = 192.168.180.0/24 192.168.191.0/24 127.0.0.0/8
[::ffff:127.0.0.0]/104 [::1]/128
myorigin = /etc/mailname
readme_directory = no
recipient_delimiter = +
relayhost = 192.168.180.5
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated
defer_unauth_destination
smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_protocols = !SSLv2, !SSLv3
smtpd_tls_security_level = may
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
virtual_alias_domains = dummy.local, intern01.local, intern02.local
virtual_alias_maps = hash:/etc/postfix/virtual
postconf -Mf
smtp inet n - y - - smtpd
pickup unix n - y 60 1 pickup
cleanup unix n - y - 0 cleanup
qmgr unix n - n 300 1 qmgr
tlsmgr unix - - y 1000? 1 tlsmgr
rewrite unix - - y - - trivial-rewrite
bounce unix - - y - 0 bounce
defer unix - - y - 0 bounce
trace unix - - y - 0 bounce
verify unix - - y - 1 verify
flush unix n - y 1000? 0 flush
proxymap unix - - n - - proxymap
proxywrite unix - - n - 1 proxymap
smtp unix - - y - - smtp
relay unix - - y - - smtp
-o syslog_name=postfix/$service_name
showq unix n - y - - showq
error unix - - y - - error
retry unix - - y - - error
discard unix - - y - - discard
local unix - n n - - local
virtual unix - n n - - virtual
lmtp unix - - y - - lmtp
anvil unix - - y - 1 anvil
scache unix - - y - 1 scache
maildrop unix - n n - - pipe flags=DRhu
user=vmail argv=/usr/bin/maildrop -d ${recipient}
uucp unix - n n - - pipe flags=Fqhu
user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
ifmail unix - n n - - pipe flags=F user=ftn
argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
bsmtp unix - n n - - pipe flags=Fq.
user=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient
scalemail-backend unix - n n - 2 pipe flags=R
user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop}
${user} ${extension}
mailman unix - n n - - pipe flags=FR
user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py ${nexthop}
${user}
--- Begin Message ---
hhhhhhhhhhhhhiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiijjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbcccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffgggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggghhhhhhhhhhhhhhhhhhhhh
Date: 2020-11-03
There is not much interesting stuff going on here.
Just some regular email plain text.
--- End Message ---
postconf -n
alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
append_dot_mydomain = no
biff = no
compatibility_level = 2
inet_interfaces = all
inet_protocols = all
mailbox_size_limit = 0
mydestination = $myhostname, localhost
myhostname = AAAA.AAAAAA.AAAAA.AA
mynetworks = 192.168.191.0/24 192.168.180.0/24 127.0.0.0/8
[::ffff:127.0.0.0]/104 [::1]/128
myorigin = /etc/mailname
readme_directory = no
recipient_delimiter = +
relayhost = 192.168.180.10
smtp_tls_CApath = /etc/ssl/certs
smtp_tls_security_level = none
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated
defer_unauth_destination
smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_security_level = may
virtual_alias_domains = intern03.local
virtual_alias_maps = hash:/etc/postfix/virtual
postconf -Mf
smtp inet n - y - - smtpd
pickup unix n - y 60 1 pickup
cleanup unix n - y - 0 cleanup
qmgr unix n - n 300 1 qmgr
tlsmgr unix - - y 1000? 1 tlsmgr
rewrite unix - - y - - trivial-rewrite
bounce unix - - y - 0 bounce
defer unix - - y - 0 bounce
trace unix - - y - 0 bounce
verify unix - - y - 1 verify
flush unix n - y 1000? 0 flush
proxymap unix - - n - - proxymap
proxywrite unix - - n - 1 proxymap
smtp unix - - y - - smtp
relay unix - - y - - smtp
-o syslog_name=postfix/$service_name
showq unix n - y - - showq
error unix - - y - - error
retry unix - - y - - error
discard unix - - y - - discard
local unix - n n - - local
virtual unix - n n - - virtual
lmtp unix - - y - - lmtp
anvil unix - - y - 1 anvil
scache unix - - y - 1 scache
postlog unix-dgram n - n - 1 postlogd
maildrop unix - n n - - pipe flags=DRXhu
user=vmail argv=/usr/bin/maildrop -d ${recipient}
uucp unix - n n - - pipe flags=Fqhu
user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
ifmail unix - n n - - pipe flags=F user=ftn
argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
bsmtp unix - n n - - pipe flags=Fq.
user=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient
scalemail-backend unix - n n - 2 pipe flags=R
user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop}
${user} ${extension}
mailman unix - n n - - pipe flags=FRX
user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py ${nexthop}
${user}
--- Begin Message ---
There is not much interesting stuff going on here.
Just some regular email plain text.
--- End Message ---
