Hello , sir.
not actually E2.
Dianabol as a descendant of methyl testosterone, it turns not into estrogen, but into ethyl estradiol(EE).
Link here - Llewellyn W (2011). Anabolics. Molecular Nutrition Llc. pp. 444–454, 533. ISBN 978-0-9828280-1-4.
Compared to estradiol, EE has greatly improved bioavailability when taken by mouth, is more resistant to metabolism, and shows relatively increased effects in certain parts of the body like the liver and uterus.
The bad news is: EE cannot bind to SHBG and it has a higher affinity to the estrogen receptor.
Also, the elimination half-life for usual estrogen is 60-90 minutes, while EE has 7 hours.
So its more steady, solid and will accumulate its effects longer - positive and negative both