sent an email that got marked as spam

[paul29]

I sent someone an email (from fastmail) and it somehow ended up in her spam folder. I'd earlier exchanged some email with the same person without problems. These were plain text emails about computer stuff, not imported pills or anything like that. Could one of FM's IP addresses have gotten dirty or something? I'm not sure whether to open a ticket, or just not worry about it unless it happens again.

[n5bb]

It's very difficult to give a good response without more information. Fastmail uses 5 outgoing email servers at this time with these IP addresses. All of these addresses look good (no IP blocks) at this time (using http://mxtoolbox.com/SuperTool.aspx#):

• out1-smtp.messagingengine.com 66.111.4.25
• out2-smtp.messagingengine.com 66.111.4.26
• out3-smtp.messagingengine.com 66.111.4.27
• out4-smtp.messagingengine.com 66.111.4.28
• out5-smtp.messagingengine.com 66.111.4.29

I recommend that you ask her to try to send you back the original email as she received it so you can check the headers. She can try to do this in one of these ways - since I don't know if she is using webmail (and which provider) or an email client (and which client), I can't give you exact instructions:

• Forward the original message to you as an attachment.
• Open the original email and examine the full headers. Copy/paste these full email headers into a new message to you.
• Open the original email and examine the original (raw) message content. Copy/paste this raw content into a new message to you.

Many email services show the reasons for suspecting the message as spam. For example, Gmail has these features:

• Authentication-Results header: shows DKIM, SPF, and DMARC results
• Warning message shown above the email body, such as:
  • Why is this message in Spam? It contains content that's typically used in spam messages.
  • Why is this message in Spam? It's similar to messages that were detected in our spam filters.

If you can get a copy of the original raw message, look at the full headers starting at the top. You should eventually find a header line vaguely similar to this one (from Gmail):

Received: from out5-smtp.messagingengine.com (out5-smtp.messagingengine.com. [66.111.4.29])         
by mx.google.com with ESMTPS id 133si25969527qkf.329.2016.11.25.09.59.04         
for <bill.****@gmail.com>         
(version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);         
Fri, 25 Nov 2016 09:59:04 -0800 (PST)

This shows the Fastmail server and IP address used for the delivery. Email headers are usually added at the top, so any email headers above this were added at her end. There may be authentication or other indicators as to why the message was not filed in the Inbox.

Was the email sent directly to her final delivery address, or was it in some way redirected or forwarded? Forwarding can reduce the accuracy of spam filters and cause blocking in some cases.

It's also possible that she accidentally or purposefully marked a previous message from you (or with a similar subject or message body) as spam, or some filter did this at her email provider or her email client.

Bill