Hi Cloudron Forum!
We have 3 websites hosted on Cloudron, I'll detail some email scenarios where we'd appreciate some advice / guidance from those of you who have been there already.
domain1
Manual DNS setup in Cloudron, but in Email | Status tab all is green (MX / DKIM / SPF / DMARC / PTR / outbound SMTP direct / IP address not on a blocklist)
Email relay on Outbound tab is via Built-in SMTP server
When emailing an Office 365 / Exchange Online mailbox our emails get delivered to Junk Mail; analysing the email header there is only 1 issue: DKIM Authenticated (this according to mxtoolbox); namely, from the mxtoolbox report:
dkim:domain1:cloudron-<domain1_domainkey>
DKIM public record (in green)
v=DKIM1; t=s; p=MIG...<long alphanumeric string>
DKIM signature (in red)
v=1; a=rsa-sha256; c=relaxed/simple; d=domain1; s=cloudron-<domain1_domainkey>; h=from:subject:date:message-id:to:mime-version; bh=<some body hash string>=; b=<some other long alphanumeric string>=
PS: The failed test is "DKIM Signature Body Hash Verified" and the result is "Body Hash Did Not Verify".
Why would the DKIM Authenticated element be flagged as an error? Our DKIM record is correct, so the DKIM email signature should be derived from it without any issues; the email in question is DMARC Compliant, but still it ends up in Junk on O365.
As an aside, I must note the email was sent with rich text formatting; if the email is sent to Hotmail in plain text, the email headers check out perfectly, green all round, yet the outcome is the same, still gets labelled as spam. Now, why would plain text or rich text have any bearing on the DKIM Authenticated element passing or failing as far as mxtoolbox analyse headers is concerned, to me this makes no sense at all. But it does seem to suggest the outcome is driven by something else, not just the technical setup per se.
If from Roundcube webmail we email any icloud.com address we get this bounceback message:
Final-Recipient: rfc822;<name>@icloud.com
Action: failed
Status: 5.7.0
Remote-MTA: mx02.mail.icloud.com
Diagnostic-Code: smtp;554 5.7.0 Blocked - see https://support.proofpoint.com/dnsbl-lookup.cgi?ip=<our IP address>
So whilst Cloudron says our IP address is not on a blocklist, icloud.com must have us blocked, right? Is O365 blocking us as well?
Let me link the 2 scenarios together with a surprising outcome; we have a free Mailchimp account for domain1 (we email our paying members), where domain1 is verified and authenticated as an email domain. From there we can send to icloud.com just fine (likely because Mailchimp is the sender on our behalf, so emails don't go out from our IP address) and we can deliver emails to O365 Inboxes too (the surprising element being that if you analyse the O365 email headers it's a Christmas tree of red lights: DMARC fail, SPF fail, DKIM fail, yet it gets to Inbox?!). What's the moral of this story? Mailchimp good, our Roundcube webmail bad? I'm specifically interested in deliverability to O365 and other enterprise grade email systems. Our emails get to Junk in Hotmail too, regardless of plain text or rich text, which is what makes me think that sender reputation or being blocked are just as, if not more important than our technical setup being correct, which it is.
Finally, on domain3, same setup as domain1 with the exception of a GoDaddy automatic Domain / DNS setup in Cloudron, we get pretty much the same issues, outgoing emails go to Junk. The plain text "trick" when emailing O365 does not yield a perfectly clean mxtoolbox email headers analysis, but then it seems this is not enough any way for a successful Inbox delivery. We have tried to relay through a free Mailjet account on domain3, but this was a waste of time as ultimately we discovered that the underlying Mailjet mail server was blacklisted on 2-3 sites hence the waste of time.
So, how can we send legitimate emails out successfully from Cloudron and have them reach recipients' Inboxes? We are not spammers, nor are we selling anything, so I'm keen to cover all the bases and tick all the boxes. The emails we want to send are directed at specific people to raise awareness of various topics (one email and that's it, pretty much); they engage with us, fine, they don't, fine again, bu I mention this because we can't use Mailchimp as the T's and C's of that platform (as well as others presumably) are that you can only email subscribers (and our intended audience are not subscribers, but one off / hand picked people) or else you fall fault of spam rules and legislation, hence why we are staying clear of that.
Are there other free mail relay services which can be relied upon? Or does one need to get a paid service for that level of service and end result, i.e. Inbox deliverability? At the moment, given the hit and miss results and baffling analysis of email headers, I must say I'm not really sure.
Thank you for reading and thank you in advance for any ideas / advice you have; hopefully this post proves helpful to others as well.
THI Staff