Resolved Plesk to Plesk mail migration - can't setup accounts on smartphones

[jwvdmei]

Hostname mailing.iburo.nl (Server 1)
IP address 193.219.116.202
OS ‪ ‪ ‪ Debian 7.11‬
Plesk version 12.5.30 Update #79, last updated at Dec 19, 2018 06:27 AM


Hostname mailing.iburo.nl (Server 2)
IP address 149.210.249.39
OS ‪ ‪ ‪CentOS Linux 7.6.1810 (Core)‬
Product Plesk Onyx
Version 17.8.11 Update #35, last updated on Dec 29, 2018 11:11 PM

I have just migrated mail from server 1 to server 2 using the Plesk Migration & Transfer Manager.

In Plesk on server 2 everything seems to be there: subscriptions and email addresses.
The server has a let's Encrypt certificate and I want clients to pick-up mail with this domain: mailing.iburo.nl.
Logging in via the webmail works as well and I can see email messages are being delivered to the inbox.

Problem: When I want to set an email account up on an android phone I get this message: your username or password is incorrect. However the same login details work with webmail.

• I have checked "username and passwords" quite a few times ,
• I have also checked to see if all the DNS zones are pointing towards server 2, which they are.
• I have re-sync the subscriptions a number of times.

With another test email account from another subscription on the same server (2) there seems to be no problem verifying the account.

One subscription (mailing.iburo.nl) has the same domain as the hostname on server 2.

Your help would greatly appreciated, thank you..