Hi. There is a closed topic with subject " Change password emails going to spam " which looks very similar to what I am experiencing now. It is not all the emails that end up not being delivered, but it started happening regularly within 1-2 weeks.
Its critical for our users. They cant complete signup and those who forgot their passwords, cannot login. It is hurting out business of course.
Here is an example of what my STMP server returns to me (I removed the actual email address)
This message was created automatically by mail delivery software.
A message that you sent has not yet been delivered to one or more of its
recipients after more than 24 hours on the queue on sto1.spamfilter.cc.
The message identifier is: 1glz28-000BZJ-0W
The subject of the message is: Reset your password
The date of the message is: Tue, 22 Jan 2019 16:36:15 +0000
The address to which the message has not yet been delivered is:
No action is required on your part. Delivery attempts will continue for
some time, and this warning may be repeated at intervals if the message
remains undelivered. Eventually the mail delivery software will give up,
and when that happens, the message will be returned to you.
Reporting-MTA: dns; sto1.spamfilter.cc
(… more stuff…)