Sending email from Plone without 'getting marked as spam'

I want to sent some (very basic) emails from Plone (to all users (members)). Usually a link to a page/document on the website.

Does anyone have advice on how to avoid it to be marked as spam (as much as possible).

My users are 60+ years and it is hard to explain why they do not get it.

Would using Mailchimp or something else be a better choice ?

Figure out why these mails are marked as spam. Looking at the SMTP headers should provide some evidence.

You should use a SMTP server which is allowed to send mails for the sender's domain. For example if the sender's mail address is john@example.com then the IP address of the SMTP server should be mentioned in the SPF record of the domain example.com.

See for example: https://postmarkapp.com/blog/explaining-spf

In other words: Don't send in the name of gmail.com or other domains which are not in your hand because most of the mail servers out there will put such kind of mails directly into the spam folder or simply do not receive them at all.

Thanks a lot.

So when my customer registers his domain with domainname.shop I can add the IP-address to the 'DNS(etc.)settings for hisdomain.com and send the email from post@hisdomain.com – and I will get less mail going to spam (etc) (?)

Yes, but your mailserver, e.g. postfix, also has to answer with the correct name in its HELO message if I am right.

An SPF record is the same as a TXT record for a domain.
It looks similar to this:

v=spf1 a mx ptr ip4:1.2.3.4/32

Or use a generator like this: https://www.spf-record.com/generator

This site is work in progress, but adding a mail account for the customer ( post@customersdomanin.com) and using that instead of their gmail account seems to help a lot ( for example if I send it to me).

If your mail server supports it, implement DKIM. You can use a LetsEncrypt certificate for this purpose.

Convert your LE private key like this:
openssl rsa -inform PEM -outform PEM -in privkey.pem > rsa-privkey.pem

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