Not sure how many emails you send a day, but I signed up for sendgrid almost immediately after I learned it existed.
ISPs have lots of arbitrary policies. For periods of time my emails have been blocked from AOL and AT&T accounts, which make for a lot of headaches and support emails to deal with. (I'm just sending out forum registration, activation and thread subscription emails. no mass mailings.) For a while, we just told people to use non-AOL addresses.
Also, I haven't noticed a delay in email deliverability. It seems to deliver quickly.
Edit: If it matters, for reference, my forum sends out 6000-7000 emails a day.
ISPs have lots of arbitrary policies. For periods of time my emails have been blocked from AOL and AT&T accounts, which make for a lot of headaches and support emails to deal with. (I'm just sending out forum registration, activation and thread subscription emails. no mass mailings.) For a while, we just told people to use non-AOL addresses.
Also, I haven't noticed a delay in email deliverability. It seems to deliver quickly.
Edit: If it matters, for reference, my forum sends out 6000-7000 emails a day.