[ams6110]

Be very careful using a "free" tier on any email service if you care about reliable delivery. These are naturally utilized by people sending spam, so the mail servers used by the free tier plans tend to get a low(er) reputation. I had this issue with Mailgun, which otherwise is a fantastic service.

[linkmotif]

Mailgun has a whole FAQ type thing about sharing IPs vs getting dedicated. They kind of claim an opposite/divergent thing from what you write. They say using shared as you build domain reputation can help because you pool with more established senders. Did you find that not to be true? Are there many spammers in that pool? Should I just go dedicated right away?

[scaryclam]

I find that mailgun is highly protective over thier IP reputation, so unless you actually run into an issue yourself, don't bother with dedicated. Some spammers may use them but I've not seen much evidence of it.

[ploggingdev]

Just curious so can you explain what was the issue you faced using the Mailgun free plan? I have used their free plan in the past and never faced issues with reliable delivery and the emails were never marked as spam.

[ams6110]

This was about 8 months ago -- had never used Mailgun before. I was seeing nearly 30% "dropped" messages (rejected by receiver due to sender reputation). They did move me to another IP which worked much better, but the first impression on users was already made. I didn't push it too much because after all I wasn't paying for it so didn't really have much standing to complain.

[scaryclam]

Did you warm up your mailing list? I've seen an issue before, but it was down to our domain being new for email and us not knowing to gradually ramp up the emails instead of sending many from the get go.