I operate a small mail server for my private emails, some friends who have websites and two NGOs. In total my server sends between 60 and 400 messages a day. Now a lot of these emails are personal mails, between two or more people who know each other. Occasionally (usually once or twice a week) there will be a mailing that goes out to "members" of one NGO, informing them what's new etc.
Now I have already moved off the "mass mailings" (about 100 recipients, all personally known and manually subscribed through a paper form) to mailgun.org.
I still get (and increasingly so), rejected messages. Especially big email providers like Gmail, Yahoo or Microsoft (hotmail, live.com, ...) just decide to reject with a 550 or send personal messages to the Spam folder of the recipients. Sometimes this happens:
- gmail user sends email to user on my system
- user on my system replies
- the reply is being rejected or sent to spam
Things I have done:
- set up DKIM (per-domain signing of all outgoing email)
- set up SPF, domains usually have
- I have a correct PTR for my mail server IP
- obviously no open relay, users can only send from their own email address after authentication
- I have DMARC policies for most of the domains
- I rate limit outgoing messages, for some mail servers down to 1 per minute
- mail test services report "perfect" scores (all pass) for all of the above
- I regularily check my IP for blacklisting using http://www.dnsbl.info - it's always all green
Now the paradox comes here: for most of the big mail providers, there is a way to register to monitor rejection rates and IP reputation:
- and I believe Yahoo has something similar
but I do not classify as bulk sender, because of the low volume. So I did register to monitor my reputation and rejection rates, but because I do not send bulk email, there are no reports.
Is there anything else I can do to improve mail delivery rates? Or should I give in and stop trying to operate my own mail server?
In case it is relevant: I use postfix and have very strict rules about incoming mail (i.e. no unknown domains/host names or invalid SPF records, I use spamassassin etc.)
Here is an example, sent from me to my in-laws and it arrived in their SPAM folder: http://pastebin.com/BC6YgjpQ (I replaced the sending address domain with
example.com and the receivers address with
Since the question came up: Connections to Gmail are
Untrusted TLS connection established to gmail-smtp-in.l.google.com[2a00:1450:400c:c0b::1b]:25: TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits) encrypted.