1) If what you need from Alex is a thing that Alex needs to make happen, track in your JIRA or whatever. Make the fact that Alex's task is a DEPENDENCY that is BLOCKING you visible to the stakeholders. Alex may have multiple competing priorities, and you won't be able to champion yours without giving the stakeholders insight, so they can prioritize.
2) If people are just generally not responding to email/slack, you need to train them to. With email, I give people one day. If there's no answer, they get a follow up. After one more day, if there's no answer, they get a CC to their manager. Simply "ack"-ing these types of requests is a mandatory communication skill.
For further actions, you may consider blocking this person and/or reporting abuse
We're a place where coders share, stay up-to-date and grow their careers.
A few things:
1) If what you need from Alex is a thing that Alex needs to make happen, track in your JIRA or whatever. Make the fact that Alex's task is a DEPENDENCY that is BLOCKING you visible to the stakeholders. Alex may have multiple competing priorities, and you won't be able to champion yours without giving the stakeholders insight, so they can prioritize.
2) If people are just generally not responding to email/slack, you need to train them to. With email, I give people one day. If there's no answer, they get a follow up. After one more day, if there's no answer, they get a CC to their manager. Simply "ack"-ing these types of requests is a mandatory communication skill.