I've been using guerrillaMail for months, it's very responsive in troubleshooting issues that have presented over time (expectations). They also helped me set up an SPF record so my domain wasn't blacklisted from sending emails to non-subscribers. It's quite pricey compared with other options at comparable quality. Consider their pricing before spending your budget! Guerrillamail has been solving business communication problems of our organization since we started integrating them back in September 2018. Issues pertaining to multiple channels - the web or mobile applications; email services; slack/hipchat; zendesk ticketing platform; SMS messaging. I love how easy it is to use, my only gripe would be that you can't set up recurring emails if they don’t already exist in your mailbox (e-mail). If anything gets sent through this service then people will think its real! Its so simple for anyone who doesn' t know much about e mail or techy stuff as well which means more sales/ leads etc It has also opened me some new business opportunities by helping get clients names out there quicker than we used too before using guerrilla mailing services.