Unable to email anyone from my primary domain name; thanks Google Mail and G Suite.

[lists.nanog at monmotha.net (Brandon Martin)]

On 10/23/19 8:18 PM, Constantine A. Murenin wrote:
> A long message about how sending arbitrary operational text data to gmail can cause unsuspected problems

This is a perfect example of why service providers, IT consulting 
outfits, etc. really need to either run their own mail infrastructure or 
contract with an outfit that can handle their unique requirements. 
Google, etc. is obviously going to have things very much set up for 
their normal use case, and their infrastructure is so large that I'm 
totally not surprised that the sender RHS reputation system doesn't talk 
to the user configuration's "alternative FROM address" nor interact with 
the UI's presentation (or lack thereof) of URI-like text as clickable links.

I've had this discussion with at least one service provider I help 
manage.  There was a desire to use G Suite for email since it was 
simple.  Glad I was not crazy in counseling them that it was a 
potentially bad idea (for this and other reasons).

Another bizarre example: I have a client who uses mimecast for their 
email.  I simply cannot email them attachments whose names end in .7z. 
No amount of whitelisting my address, FROM domain, MX, etc. will make 
them get through to the inbox.  They get silently spambinned every time. 
  Send the same content in a .zip (even if it's actually a 7zip file), 
and it's fine.  Somebody probably bolted a filter on the front of 
everything to handle some attack years ago that just says ".7z bad, umkey?".
-- 
Brandon Martin