Understanding the logs is key to understanding what is going on.
This camera was setup for Motion trigger and DeepStack AI. In the above log snippet, norman (camera name) detected motion at 10:03:11.239 AM.
DeepStack identified a car at 10:03:11.546 AM. The camera was set to sample the Motion leading edge in addition to the trigger leading edge, thus the two DeepStack calls very close in proximity. At 10:03:12.720 AM an email alert was sent. Note the gap between the MOTION event and the Alert should not be more than 1-2s.

If the logs state alerts are being sent, then you can be confident the camera is triggering on motion and alerts are being sent by BI.
The issue must reside with your email server settings or your email provider.

Send alternative alerts
If you are only sending one type of alert, e.g. an email notification, create an SMS alert to try and isolate the issue. Does the SMS alert work?

If the logs state the camera triggered (i.e. Motion event in logs) and NO alerts are being sent, then you can be confident there has to be an issue with Server permissions. As stated above, double check your Profiles and Trigger and Zones section of the Email alert dialog.

If the logs state the camera did NOT trigger (i.e. no Motion event in logs) then you will have to revisit your Trigger tab settings.

Troubleshooting
If there are issues with the image attachments for example some frames are black, the underlying cause is often the video stream. Either frames are not available when the email is being generated or the encoding is causing errors. Confirm the camera window has no warning symbols and the video stream has no issues. The Live view article has details.


Issue
Confusion arises when dual streams are connected to the camera. Users may want high-res images or they may be fine with low res images. This section provides clarity as to what to do to meet your needs.


Background info
The thumbnail image which is actually stored in the database and associated with the Alert is 240px.
In earlier versions of 5.x, the thumbnail image was 480px, but the increased size really did not add much value, but did eat up database storage so was changed back to 240px.

The fix
To get higher resolution main stream Alert images, select Hi-res JPEG files for Add to alerts list:. Camera settings -> Trigger tab.


Dual streams
If your camera has dual streams and Hi-res JPEG is selected (as stated above), but the alert image is not the higher resolution image, the issue is often the main stream does not have the corresponding key frame. If the hi-res (mainstream) alert could not be saved, the software will use the alert image which is cached in memory (sub stream if camera has dual streams).

The fix is setting an appropriate pre-trigger buffer size.

Server errors
If the above two fixes do not resolve the issue, right click on an alert -> Open containing folder.
Is the corresponding JPEG the correct resolution? 240p is what's in the database. However if there's a hi-res JPEG file, this should be served instead.

If the Open containing folder selection is greyed out, then there is an issue.

• The most obvious cause is you did not set Add to alerts list = Hi-res JPEGfiles
• OR There is an issue with the setup of the Alerts folder (image below), folder permissions or something else.
  Check the log for errors, in particular Storage errors.

Note on email alerts
Email alerts provide many more options.
The Motion leading-edge image will always come from the sub stream.
The Trigger leading-edge, aka the Alert image, will only be high-res if you select Hi-res JPEG (as stated above) AND the main stream has a key frame in the buffer (thus, the need for a pre-trigger buffer as stated above).
The Additional images will always be hi-res (if you have a main stream key frame in the buffer).
Finally, the Email alert dialog also provides quality controls (default is 50/50) which can alter the alert image.