Messages to Plus Net rejected as spam

[#1]

Not a Plus Net customer now, but I've just had a couple of emails to PlusNet customers rejected as spam.

They are routine emails sent automatically by a PHP script every week to volunteers at a community library for which I run a web site. I've had no problem with the emails for years. When I set it up I tested sample messages with mail-tester.com and they have a perfect score for SPF, DKIM, DMARC, content, headers, host names and IP addresses. They are sent as HTML - only (not my choice, but previous webmaster wrote the script that way) and contain no links or attachments.

Is there someone I can contact to send a copy of the rejection info and offending message and find out if there's anything I can do to prevent Plus Net from bouncing them?

And why suddenly now - has something changed?

I will contact the recipients (who I know personally) to check they haven't changed anything like their spam filtering level.

[#2]

Hello,

A good set of questions.  SPF, DKIM and DMARC are but one set of the helpful things to do ... but that will not fix a reputation issue with your email hosting provider.

My Church uses AWS as their hosting provider and we cannot send emails to @outlook.com, hotmail.co.uk, live.co.uk and sometimes to Plusnet accounts.  We are advised that the AWS platform has a poor reputation and will not be whitelisted.

Have you checked the reputation of your sending SMTP server [IP address(ess)]?

It has been advised that the front line support staff have a new process for handling queries such as this ... though I'm not sure how they might handle an enquiry from a third party.  If you want to give them a call and see how they handle your call.  If there's any confusion, as them to "Ask Albert".

@NickBS 

[#3]

I did a quick check to see if my server is on any block lists and it was clear.

I run my own server on a VPS (not AWS though, I've heard that has a bad reputation)

I'll see if I can find an online reputation checker for a second opinion...

[#4 · Accepted solution]

Yes, my SMTP server's IP address is not on any blacklists I can find.

Anyway, this is now resolved. Following a clue seen elsewhere, I've changed from the PHP mail() function to the PHPMailer class, which by default sends a multipart/alternative message (i.e. both HTML and plain text) if you give it an HTML message body.

With otherwise similar headers, this seems to have fixed it!

I don't know why. HTML-only mails are quite common, but maybe PHPMalier is doing something else that the Plus Net mail likes better than the previous messages.

[#5]

Glad you got it sorted.

Is there any reason you send the HTML part at all? You say the emails contain no links or attachments; HTML just adds unnecessary junk. Can you not send plain-text-only?

I have my email software set to display the plain text version of any multipart email by default (I can always choose to view the other part). More than once, I've found an organisation sending multipart messages where the content of the two parts was different - unknown to them! The silliest was a newsletter, where I was asking why are you telling me about forthcoming events that have already happened - I eventually worked out that their system was sending, in the plain text part, the fixed content of an edition of the newsletter from many editions ago.

Also, some systems are very rude: they just put in the plain text part something like "we tried to send this as HTML (pictures and text), but you are not receiving it." Even when the HTML part contained nothing that actually needed HTML anyway. Again, the person sending often doesn't know this is happening.

[#6]

Good question! I don't even like using HTML for email. It's a community library web site that was created and maintained by someone' who now doesn't have time or inclination to  continue, so I:ve taken it over. The mails are sent to library volunteers by a PHP script running as a daily cron job. I could switch to plain text and I don't know if the volunteers would complain, though they'd certainly notice the typographical differences.

A bit more searching has revealed that pure HTML only emails do get high spam scores on some systems, confirming that may be why Plus Net was rejecting them.

There are no images, but some of the messages contain a link.  That wouldn't be a problem, as  most mailers will display an https: url as an active link. Maybe I'll switch to text/plain and see if anyone says anything 🙂