Still problems/questions for postfix and dovecot

Discussion in 'ISPConfig 3 Priority Support' started by schmidtedv, Mar 20, 2017.

  1. schmidtedv

    schmidtedv Member HowtoForge Supporter

    We have an external crm system that uses IMAP for sending mails. The System is already a bit older, but worked now for years together with ISPConfig (courier) and Debian 6. Some weeks ago I moved all mailconfig over to our new Server with Ubuntu 16.04 (ISPConfig Howto, dovecot). This was done by create all accounts manually, so should be ok.
    The Problem I have now is when the crm is sending over 100 mails at once, somehow the connection gets lost. I can send 100 mails and have to send the rest again.
    Could it be, that the crm is using an older TLS that breaks the connection, or would it then throw out an error right at the beginning?
    Could there be to many connects with dovecot/postfix and IMAP so that this has to be configured higher? The crm has about 40 IMAP-User-Accounts and on top, of course, is sending/receiving mail.

    In I already did this - probably useless - change:
    smtpd_client_message_rate_limit = 500​

    In I have a question. When I install from the HowTo the following line shows up:
    amavis unix - - y - 2 smtp​
    This line is different in your VMware-Image:
    amavis unix - - - - 2 smtp​
    Which line is right?

    In dovecot.conf I changed the following:
    mail_max_userip_connections = 500
    default_vsz_limit = 1024M
    service imap-login {
    service_count = 0
    client_limit = 1024
    process_limit = 512
    process_min_avail = 4
    service pop3-login {
    service_count = 0
    Is this ok, or would/can I check other things to optimize the connects from 1 IP?

    Actually, my install is showing this line at the bottom of the file (the VMware Image doesn't):
    mail_plugins = $mail_plugins quota​
    Is this right or shouldn't it be there?
  2. till

    till Super Moderator Staff Member ISPConfig Developer

    Sending is done trough postfix, so if there is an issue in the mail config, then it must be in the postfix config files and not dovecot.

    Both can be ok, depending on the actual setup. The setting on your systm is ok, otherwise you wont be able to send emails at all.

    Did you try to send without tls?
  3. schmidtedv

    schmidtedv Member HowtoForge Supporter

    Well, I tried both and both seem to work, it's just specifying that amavis should run chrooted or not, am I right? If that's the difference, then how is your howto made up...should it be chrooted or not?

    Yes, but I'm not shure if I tried with 100 and above. Although I still have another problem with getting blocked every couple weeks by Hotmail or AOL (don't know why), I can send mails. It's just not clear to me, why there is a breakdown in the sending-process from crm to the server (thats new to me, never got that with Debian 6 before).

    What about this I have to care? Also here the config doesn't seem to make any difference with or without this extra line at the bottom of the file, but, compared with your VMware-Image, I don't know where or why it might come from.
  4. till

    till Super Moderator Staff Member ISPConfig Developer

    As you found out, you can run amavis with and without chroot and both options are fine and this option is neither set by me in the howto nor by ISPConfig, it is set by the maintainer of the amavisd-new package and it is possible that he changed the default between your setup was made and my vmware image was made.

    Both mail services have very strict spam filters and it is enough that one of your mail receivers clicks on the spam link in hotmail or AOL to get you blocked there. This does not has to be related to your server setup. All you can do to avoid being blocked is to setup a correct reverse record, setup spf, setup dkim and ensure to not send mass emails too fast and of course to not send any spam.

    Or you get an account at a service like sendgrid, for mail amounts up to 40 thousand emails they offer a free account:

    Just leave everything as it is set by ISPConfig. This is not related to mail sending, this setting is about mailbox size restrictions, so altering it will not make any difference on mail sending.
  5. schmidtedv

    schmidtedv Member HowtoForge Supporter

    Lol, thanks...something I didn't think of!

    ok, will leave it in

    For AOL and Hotmail I'm already in contact with their postmasters...still not satisfactory, but I'm working on. If I have some more questions on my situation with DKIM DMARC and SPF, I will open another thread, thanks Till!

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