Почему могут долго идти письма с exim4 и попадать в спам? Вот пример из отправки на gmail
2016-09-18 14:28:53 1blaHF-0001Eh-OS <= www-data@domain.ru U=www-data P=local S=9977
2016-09-18 14:31:01 1blaHF-0001Eh-OS gmail-smtp-in.l.google.com [2a00:1450:4010:c02::1b] Connection timed out
2016-09-18 14:31:02 1blaHF-0001Eh-OS => mymail@gmail.com R=dnslookup T=remote_smtp H=gmail-smtp-in.l.google.com [74.125.205.27] X=TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128 DN="C=US,ST=California,L=Mountain View,O=Google Inc,CN=mx.google.com" C="250 2.0.0 OK 1474198262 8si8013731lff.273 - gsmtp"
2016-09-18 14:31:02 1blaHF-0001Eh-OS Completed
Еще не много напрягает это
2016-09-18 14:32:34 Start queue run: pid=6172
2016-09-18 14:32:34 1blZyw-0007v2-Ap == www-data@domain.ru R=local_user T=maildir_home defer (13): Permission denied: cannot create /var/www/Maildir
2016-09-18 14:32:34 End queue run: pid=6172
2016-09-18 14:09:56 1blZyu-0007ux-FH <= www-data@domain.ru U=www-data P=local S=9956
2016-09-18 14:09:58 1blZyu-0007ux-FH ** mymail@mail.ru R=dnslookup T=remote_smtp X=TLS1.2:RSA_AES_128_GCM_SHA256:128 DN="C=RU,ST=RUSSIAN FEDERATION,L=Moscow,O=LLC Mail.Ru,OU=IT,CN=*.mail.ru": SMTP error from remote mail server after end of data: host mxs.mail.ru [217.69.139.150]: 550 spam message rejected. Please visit *link* or report details to abuse@corp.mail.ru. Error code: *code*. ID: *ID*.
2016-09-18 14:09:58 1blZyw-0007v2-Ap <= <> R=1blZyu-0007ux-FH U=Debian-exim P=local S=11144
2016-09-18 14:09:58 1blZyu-0007ux-FH Completed
domain.ru. MX 10 mail.domain.ru
domain.ru. MX 20 mail.domain.ru
domain.ru. TXT "v=spf1 ip4:myip a mx ~all"