Working with Japanese colleagues and customers, you calling everyone by their last name with the suffix "-san". In discussions even when the person is not present, Americans still say "Abe-san" since it is how you always address them. Is "-san" only supposed to be used when you are addressing the person? I'm unsure on the correct way to use it.
You should -san the outgroup (including when speaking about them in the 3rd person); you should not -san the ingroup. Whether someone is outgroup or ingroup depends on who you're talking to and can change.
There are other options as well.
In general, Americans who are rubbing up against Japanese people in a not-specifically-Japanese context get lots of leeway on this question. (One has to be good if one works as a full-time employee of a traditionally managed Japanese corporation; if one is entertaining a delegation from Japan at a US event, one gets a lot of kudos for trying.)
Note also that there are some people with preferences here, including some preferences which aren't necessarily socially normative.
If I’m talking to you, who does not work at Stripe with me, and I promise a call from a named coworker, I would call them by their last name with no honorific. This is because my coworker is an ingroup when speaking to anyone outside the company in a business context (the outgroup).
If I were talking about that coworker with a member of my team, in most plausible cases the 3rd party coworker is the outgroup in that discussion, and I would refer to them as $NAME-san.
San could be translated into mr/ms and you drop it off pretty much only when you’re close enough with the person you’re describing. If you use just the last name it will sound “Oh yeah, i had meeting with Mikey” if you’re referring to person called Mike Miller. First name is usually only used by really close friends and lovers.
The other time is when you’re using some other suffix with them, eg. you refer to them by profession.
