Deliverability issues with Outlook Group email addresses

[Kimi_Heskett1]

We use our outlook exhange email groups to email groups of our own employees and sometimes want to use that group address in Marketo to include them on certain mailings. Example, I want to send my group-sales@mycompany.com an email about an acquisition in Marketo as part of a bigger list. That way I'm not always having to import everyone on the group sales list and want to let our exchange servers to the work and parse it out. 

I'm guessing this is not a best practice but can be ideal in a pinch.

We see varied deliverability when doing this however. Sometimes it works fine. Sometimes half the group gets the message and half does not. Sometimes it gets put in the quarantine folder. 

Anyone else do a similar practice or have any insight? There doesn't seem to be any method to the madness for these. 

The only other discussion on this I could find in here was this one.

[Anonymous · Accepted solution]

The Outlook Junk E-mail filter is sensitive to a large number of identical emails arriving at one time and once the threshold is reached will flag the rest of the emails as Junk.  This may be a factor, but if your Outlook Server is managed by a third party, it may be difficult to customize the settings that affect this.  However, if you white list the sender, it should by-pass this filter.

You may also want to consider throttling your email as described in the Throttle Email Delivery help article.